Communication method, and transmitting apparatus and receiving apparatus using that communication method

ABSTRACT

A method for use in a communication apparatus that receives an orthogonal frequency division multiplexing (OFDM) signal transmitted from a base station. The OFDM signal includes a plurality of carrier groups each comprising a plurality of carriers, the plurality of carrier groups being assigned transmission data for a plurality of communication apparatuses. Each of the plurality of carrier groups adopt one of a first frame configuration, where the transmission data is transmitted using one modulation signal, and a second frame configuration, where the transmission data is transmitted using a plurality of modulated signals. The method includes specifying a carrier group to which transmission data for the communication apparatus is assigned, based on control information included in the received OFDM signal and generating reception data associated with the specified carrier group based on one of the one modulated signal used in the first frame configuration and the plurality of modulated signals used in the second frame configuration.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer. No. 12/417,284, filed Apr. 2, 2009, which is continuation of U.S.patent application Ser. No. 10/516,937, filed Dec. 14, 2004 (now U.S.Pat. No. 7,570,626, issued on Aug. 4, 2009), which is a National StageApplication of International Application No. PCT/JP03/09011, filed Jul.16, 2003, and claims priority under 35 U.S.C. §119 of Japan ApplicationNo. 2002-206799, filed Jul. 16, 2002, and Japan Application No.2002-259791, filed Sep. 5, 2002, the disclosure of each of which isexpressly incorporated herein by reference in its entirety. TheInternational Application was not published in the English Language.

TECHNICAL FIELD

The present invention relates to a communication method, and atransmitting apparatus and receiving apparatus that use thatcommunication method.

BACKGROUND ART

FIG. 1 is a block diagram showing the configuration of a conventionalradio transmitting apparatus and receiving apparatus. A modulated signalgeneration section 02 has a transmit digital signal 01 as input, andoutputs a modulated signal 03.

A radio section 04 has a modulated signal as input, and outputs atransmit signal 05.

A power amplification section 06 has transmit signal 05 as input,amplifies transmit signal 05 and outputs amplified transmit signal 07,and then amplified transmit signal 07 is output as a radio wave from anantenna 08.

A radio section 11 has as input a received signal 10 received from anantenna 09, and outputs a received quadrature baseband signal 12.

A demodulation section 13 has received quadrature baseband signal 12 asinput, and outputs a received digital signal 14.

Thus, in a conventional apparatus, a plurality of modulated signals arenot multiplexed.

Also, when a plurality of modulated signals are transmitted and aremultiplexed, and the transmitted multiplexed signals are separated anddemodulated by the receiving apparatus, it is necessary to performhigh-precision separation and demodulation.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a communicationmethod that enables compatibility between data transmission speed andreceived data quality to be achieved, and a transmitting apparatus andreceiving apparatus that use that communication method.

This object is achieved by improving the data transmission speed byhaving a transmitting apparatus transmit a plurality of modulatedsignals multiplexed, and a receiving apparatus separate and demodulatethe transmitted multiplexed modulated signals. Also, by configuring inaccordance with either a method whereby one modulated signal of acommunication system is transmitted, or a method whereby a plurality ofmodulated signals of a communication system are multiplexed andtransmitted, by frequency and time, it is possible for a communicatingparty to obtain information accurately by transmitting information ofhigh importance by means of a method whereby one modulated signal of acommunication system is transmitted. Moreover, by performingcommunication by frequency or time of a method whereby one modulatedsignal of a communication system is transmitted, and by frequency ortime of a method whereby a plurality of modulated signals of acommunication system are multiplexed and transmitted, according to thecommunication conditions, it is possible to make informationtransmission speed and received data quality compatible.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an example of the configuration of aconventional radio transmitting apparatus and receiving apparatus;

FIG. 2 is a drawing showing an example of the frame configuration on thefrequency-time axes of each channel according to Embodiment 1 of thepresent invention;

FIG. 3 is a block diagram showing the configuration of a transmittingapparatus of this embodiment;

FIG. 4 is a block diagram showing the configuration of a receivingapparatus of this embodiment;

FIG. 5 is a drawing showing an example of the arrangement of a basestation and terminals according to Embodiment 2 of the presentinvention;

FIG. 6 is a block diagram showing an example of the configuration of areceiving apparatus of this embodiment;

FIG. 7 is a block diagram showing an example of the configuration of atransmitting apparatus of this embodiment;

FIG. 8 is a block diagram showing an example of the configuration of areceiving apparatus of this embodiment;

FIG. 9 is a drawing showing communication signal frame configurationsaccording to Embodiment 3 of the present invention;

FIG. 10 is a drawing showing a communication signal frame configurationaccording to Embodiment 3 of the present invention;

FIG. 11 is a drawing showing the base station transmit signal frequencyarrangement according to this embodiment;

FIG. 12 is a block diagram showing an example of the configuration of atransmitting apparatus of a base station according to this embodiment;

FIG. 13 is a block diagram showing the configuration of a receivingapparatus of a terminal according to this embodiment;

FIG. 14 is drawing showing an example of the configuration of areceiving apparatus of a terminal according to Embodiment 4 of thepresent invention;

FIG. 15 is a drawing showing an example of the configuration of atransmitting apparatus of a base station according to this embodiment;

FIG. 16 is a drawing showing an example of the frame configuration onthe frequency-time axes of channel A and channel B according to thisembodiment;

FIG. 17 is a drawing showing an example of the configuration of areceiving apparatus according to Embodiment 5 of the present invention;

FIG. 18 is a block diagram showing an example of the configuration of areceiving apparatus of a terminal according to Embodiment 6 of thepresent invention;

FIG. 19 is a block diagram showing an example of the transmit signalframe configuration transmitted by a base station according toEmbodiment 7 of the present invention;

FIG. 20 is a block diagram showing an example of the configuration of atransmitting apparatus according to Embodiment 7 of the presentinvention;

FIG. 21 is a block diagram showing an example of the configuration of areceiving apparatus according to Embodiment 7 of the present invention;

FIG. 22A is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 22B is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 22C is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 22D is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 22E is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 22F is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 22G is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 22H is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 23A is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 23B is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 23C is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 23D is a drawing showing an example of the signal point arrangementin the I-Q plane when a channel B signal undergoes differential encodingwith respect to a channel A signal;

FIG. 24A is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 24B is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 24C is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 24D is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 25A is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 25B is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 25C is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 25D is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 26A is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 26B is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 26C is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 26D is a drawing showing an example in which channel B M-arymodulation I-Q plane signal point arrangement is performed based onchannel A PSK modulation;

FIG. 27 is a drawing showing an example of base station transmit signalframe configurations of this embodiment;

FIG. 28 is a drawing showing an example of pilot symbol signal pointarrangement in the I-Q plane according to this embodiment;

FIG. 29 is a drawing showing an example of base station transmit signalframe configurations according to this embodiment;

FIG. 30 is a drawing showing an example of the configuration of areceiving apparatus according to this embodiment;

FIG. 31 is a block diagram showing an example of a demodulation sectionof this embodiment;

FIG. 32 is a block diagram showing an example of a demodulation sectionof this embodiment;

FIG. 33 is a block diagram showing an example of a demodulation sectionof this embodiment;

FIG. 34 is a block diagram showing an example of a demodulation sectionof this embodiment;

FIG. 35 is a block diagram showing an example of the configuration of areceiving apparatus according to this embodiment;

FIG. 36 is a block diagram showing an example of a demodulation sectionof this embodiment;

FIG. 37 is a block diagram showing an example of the configuration of atransmitting apparatus according to Embodiment 8 of the presentinvention;

FIG. 38 is a block diagram showing an example of the configuration of areceiving apparatus according to Embodiment 8 of the present invention;

FIG. 39 is a drawing showing an example of base station arrangementaccording to Embodiment 9 of the present invention;

FIG. 40 is a block diagram showing the configuration of a base stationreceiving apparatus according to Embodiment 9 of the present invention;

FIG. 41 is a block diagram showing the configuration of a base stationtransmitting apparatus according to Embodiment 9 of the presentinvention;

FIG. 42 is a drawing showing an example of the configuration of aterminal receiving apparatus according to Embodiment 9 of the presentinvention;

FIG. 43 is a drawing showing an example of the configuration of aterminal transmitting apparatus according to Embodiment 9 of the presentinvention;

FIG. 44 is a drawing showing an example of base station arrangementaccording to Embodiment 9 of the present invention;

FIG. 45 is a drawing showing an example of base station frameconfigurations according to Embodiment 10 of the present invention;

FIG. 46 is a drawing showing an example of base station frameconfigurations according to Embodiment 10 of the present invention;

FIG. 47 is a drawing showing an example of the configuration of a basestation transmitting apparatus according to Embodiment 10 of the presentinvention;

FIG. 48 is a drawing showing an example of the configuration of a basestation receiving apparatus according to Embodiment 10 of the presentinvention;

FIG. 49 is a drawing showing an example of the configuration of aterminal receiving apparatus according to Embodiment 10 of the presentinvention;

FIG. 50 is a drawing showing an example of the configuration of aterminal transmitting apparatus according to Embodiment 10 of thepresent invention;

FIG. 51 is a drawing showing an example of the frame configuration of amodulated signal transmitted by a terminal according to Embodiment 10 ofthe present invention;

FIG. 52 is a drawing showing an example of the configuration of aterminal receiving apparatus according to Embodiment 10 of the presentinvention;

FIG. 53 is a block diagram showing an example of base station transmitsignal frame configurations according to Embodiment 12 of the presentinvention;

FIG. 54 is a drawing showing an example of the configuration of aterminal receiving apparatus according to Embodiment 12 of the presentinvention;

FIG. 55 is a drawing showing an example of the configuration of aterminal transmitting apparatus according to Embodiment 11 of thepresent invention;

FIG. 56 is a drawing showing an example of the frame configuration of amodulated signal transmitted by a terminal according to this embodiment;

FIG. 57 is a drawing showing an example of the configuration of a basestation transmitting apparatus according to Embodiment 11 of the presentinvention;

FIG. 58 is a drawing showing an example of the configuration of a basestation receiving apparatus according to Embodiment 11 of the presentinvention;

FIG. 59 is a drawing showing an example of the configuration of a basestation transmitting apparatus according to Embodiment 11 of the presentinvention; and

FIG. 60 is a drawing showing a sample configuration of a channelmultiplexing communication system using a beam space mode typified by aneigenmode in a MIMO system.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference now to the accompanying drawings, embodiments of thepresent invention will be explained in detail below.

Embodiment 1

In this embodiment, a description is given of a transmitting apparatusthat transmits non-multiplexed and multiplexed carriers in transmitframes in a multicarrier communication system, and a receiving apparatusthat can demodulate a modulated signal of either carrier.

FIG. 2 is a drawing showing an example of the frame configuration on thefrequency-time axes of each channel according to Embodiment 1 of thepresent invention. In FIG. 2, the vertical axis indicates frequency andthe horizontal axis indicates time. Reference numeral 101 indicates aguard symbol, reference numeral 102 indicates an information symbol,reference numeral 103 indicates an estimation symbol, and referencenumeral 104 indicates a control symbol.

In FIG. 2, guard symbols 101 are symbols for which there is no modulatedsignal. Estimation symbols 103 are pilot symbols for estimating, forexample, time synchronization, frequency synchronization, and distortiondue to the channel fluctuation, or a unique word or preamble, for whicha known signal such as a BPSK modulated signal, for example, issuitable. Control symbols 104 are symbols that transmit information usedby a terminal for control, and are symbols for transmitting informationby means of information symbols 102.

A feature of the communication method of this embodiment is that, in aparticular carrier 1, only symbols of one channel are transmitted, andinformation symbols of a plurality of channels are transmitted and aremultiplexed in other carriers.

That is to say, in FIG. 2, in carrier 1 through carrier 6, only channelA information symbols are transmitted, and in carrier 7 through carrier12, channel A information symbols and channel B information symbols aretransmitted and are multiplexed.

Similarly, in carrier 1 through carrier 6, only channel A estimationsymbols are transmitted, and in carrier 7 through carrier 12, channel Aestimation symbols and channel B estimation symbols are transmitted andare multiplexed.

A transmitting apparatus that transmits signals with the frameconfiguration in FIG. 2 will now be described. FIG. 3 is a block diagramshowing the configuration of a transmitting apparatus of thisembodiment.

A frame configuration signal generation section 221 generates frameconfiguration information based on an input control signal 223, andoutputs a frame configuration signal 222 comprising this frameconfiguration information to a serial/parallel conversion section 202and serial/parallel conversion section 212.

The part that processes and transmits a FIG. 2 channel A signal by meansof serial/parallel conversion section 202, an inverse discrete Fouriertransform section 204, radio section 206, power amplification section208, and antenna 210 is described below. In channel A, a signal istransmitted with information symbols, estimation symbols, and controlsymbols placed in carriers 1 through 12, as shown in FIG. 2.

Serial/parallel conversion section 202 converts a channel A transmitdigital signal 201 to parallel data with an arrangement in accordancewith frame configuration signal 222, and outputs a converted parallelsignal 203 to inverse discrete Fourier transform section 204.Specifically, serial/parallel conversion section 202 arrangesinformation symbols, estimation symbols, and control symbols in carriers1 through 12 as shown in FIG. 2.

Inverse discrete Fourier transform section 204 performs inverse discreteFourier transform processing of channel A parallel signal 203, andoutputs a converted signal 205 to radio section 206. Radio section 206converts signal 205 to radio frequency and creates a transmit signal207, and outputs transmit signal 207 to power amplification section 208.

Power amplification section 208 amplifies the power of transmit signal207, and a power-amplified transmit signal 209 is transmitted fromantenna 210 as a radio wave.

Next, the part that processes and transmits a FIG. 2 channel B signal bymeans of serial/parallel conversion section 212, an inverse discreteFourier transform section 214, radio section 216, power amplificationsection 218, and antenna 220 will be described. In channel B, a signalis transmitted with guard symbols placed in carriers 1 through 6, andinformation symbols, estimation symbols, and control symbols placed incarriers 6 through 12, as shown in FIG. 2.

Serial/parallel conversion section 212 converts a channel B transmitdigital signal 211 to parallel data with an arrangement in accordancewith frame configuration signal 222, and outputs a converted parallelsignal 213 to inverse discrete Fourier transform section 214.

Inverse discrete Fourier transform section 214 performs inverse discreteFourier transform processing of parallel signal 213, and outputs aconverted signal 215 to radio section 216.

Radio section 216 converts signal 215 to radio frequency and creates atransmit signal 217, and outputs transmit signal 217 to poweramplification section 218.

Power amplification section 218 amplifies the power of transmit signal217, and a power-amplified transmit signal 219 is transmitted fromantenna 220 as a radio wave.

Thus, in a particular channel, carriers are divided into carriers inwhich guard symbols are placed and carriers in which information symbolsare placed, and in another channel, information symbols are done awaywith in all carriers, and the same carriers are shared (multiplexed) bya plurality of channels.

The operations whereby the transmitting apparatus in FIG. 3 transmitssignals with the frame configurations in FIG. 2 will now be described.

Serial/parallel conversion section 202 has transmit digital signal 201and frame configuration signal 222 as input, and places symbols inaccordance with the channel A frame configuration in FIG. 2—that is tosay, configures a frame by placing information symbols, control symbols,and estimation symbols in carrier 1 through carrier 12, and generateschannel A parallel signal 203.

Channel B serial/parallel conversion section 212 has channel B transmitdigital signal 211 and frame configuration signal 222 as input, andplaces symbols in accordance with the channel B frame configuration inFIG. 2—that is to say, configures a frame by placing informationsymbols, control symbols, and estimation symbols in carrier 7 throughcarrier 12, and generates channel B parallel signal 213.

Estimation symbols 103 are inserted for time synchronization andfrequency offset estimation. Also, channel A carrier 1 through carrier 6estimation symbols are used by a receiving apparatus to estimatepropagation path distortion and demodulate channel A carrier 1 throughcarrier 6 information symbols. At this time, estimation symbols are notinserted in carrier 1 through carrier 6 in channel B.

Estimation symbols of channel A and channel B carrier 7 through carrier12 are symbols for separating information symbols of channel A andchannel B carrier 7 through carrier 12. For example, by using mutuallyorthogonal symbols for estimation symbols comprising channel A carrier 7through carrier 12 and estimation symbols comprising channel B carrier 7through carrier 12, it is easy to separate information symbols ofchannel A and channel B carrier 7 through carrier 12.

When channel A carrier 1 through carrier 6 information symbols andchannel A and channel B carrier 7 through carrier 12 information symbolsare compared, in the receiving apparatus channel A carrier 1 throughcarrier 6 information symbols are of better quality than channel A andchannel B carrier 7 through carrier 12 information symbols. Consideringthis fact, it is appropriate for information of high importance to betransmitted in channel A carrier 1 through carrier 6 informationsymbols. “Importance” here refers to data whose reception quality it iswished to ensure, such as modulation method or error correction methodinformation, or transmitter/receiver procedure related information, forexample.

It is also possible to transmit one kind of information medium inchannel A in carrier 1 through carrier 6, and transmit one kind ofinformation medium in channel A and channel B in carrier 7 throughcarrier 12, such as transmitting video information, for example, usingcarrier 1 through carrier 6 channel A information symbols, andtransmitting Hi-Vision video using carrier 7 through carrier 12 channelA and channel B information symbols. Also, the same kind of informationmedium may by transmitted in carrier 1 through carrier 6 channel Atransmission and carrier 7 through carrier 12 channel A and channel Btransmission. At this time, the compression ratio when coding, forexample, will be different for the same kind of information. Here, thechannel A compression ratio is lower than the channel B compressionratio.

It is also possible to transmit information in a hierarchical fashion,with a certain kind of information transmitted by means of carrier 1through carrier 6 channel A information symbols, and differenceinformation transmitted using carrier 7 through carrier 12 channel A andchannel B information symbols.

A receiving apparatus that receives a signal transmitted using the abovesymbol arrangement is described below.

FIG. 4 is a block diagram showing the configuration of a receivingapparatus of this embodiment. FIG. 4 shows one example of aconfiguration of a receiving apparatus according to this embodiment. InFIG. 4, a radio section 303 converts a received signal 302 received byan antenna 301 to baseband frequency, and outputs received quadraturebaseband signal 304 resulting from the conversion to a Fourier transformsection 305 and synchronization section 334.

Fourier transform section 305 performs Fourier transform processing onreceived quadrature baseband signal 304, and outputs resulting parallelsignal 306 to a transmission path distortion estimation section 307,transmission path distortion estimation section 309, signal processingsection 321, selection section 328, and frequency offset estimationsection 332.

Transmission path distortion estimation section 307 estimates channel Atransmission path distortion from parallel signal 306 estimationsymbols, and outputs a channel A transmission path distortion parallelsignal 308 to signal processing section 321.

Transmission path distortion estimation section 309 estimates channel Bchannel distortion from parallel signal 306 estimation symbols, andoutputs a channel B channel distortion parallel signal 310 to signalprocessing section 321.

A radio section 313 converts a received signal 312 received by anantenna 311 to baseband frequency, and outputs received quadraturebaseband signal 314 resulting from the conversion to a Fourier transformsection 315 and synchronization section 334.

Fourier transform section 315 performs Fourier transform processing onreceived quadrature baseband signal 314, and outputs resulting parallelsignal 316 to a channel distortion estimation section 317, channeldistortion estimation section 319, signal processing section 321,selection section 328, and frequency offset estimation section 332.

Channel distortion estimation section 317 estimates channel A channeldistortion from parallel signal 316 estimation symbols, and outputs achannel A channel distortion parallel signal 318 to signal processingsection 321.

Channel distortion estimation section 319 estimates channel B channeldistortion from parallel signal 316 estimation symbols, and outputs achannel B channel distortion parallel signal 320 to signal processingsection 321.

Signal processing section 321 separates parallel signals 306 and 316into channel A and channel B signals based on channel A channeldistortion parallel signals 308 and 318, and channel B channeldistortion parallel signals 310 and 320. That is to say, signalprocessing section 321 separates channel A and channel B signals ofcarrier 7 through carrier 12 in which channel A and channel B aremultiplexed in FIG. 2, outputs carrier 7 through carrier 12 channel Aparallel signal 322 to a demodulation section 324, and outputs carrier 7through carrier 12 channel B parallel signal 323 to a demodulationsection 326.

Demodulation section 324 demodulates carrier 7 through carrier 12channel A parallel signal 322, and outputs a demodulated receiveddigital signal 325.

Demodulation section 326 demodulates carrier 7 through carrier 12channel B parallel signal 323, and outputs a demodulated receiveddigital signal 327.

Selection section 328 has parallel signals 306 and 316 as input, selectsthe parallel signal with the greater field strength, for example, andoutputs the selected parallel signal to a demodulation section 330 asparallel signal 329.

Demodulation section 330 estimates channel distortion for selectedparallel signal 329 from non-multiplexed carrier 1 through carrier 6estimation symbols 103 in FIG. 2, demodulates the carrier 1 throughcarrier 6 parallel signal from the estimated channel distortion, andoutputs a demodulated received digital signal 331.

Frequency offset estimation section 332 estimates the frequency offsetamount from parallel signal 306 and 316 FIG. 2 estimation symbols, andoutputs a frequency offset estimation signal 333 to radio section 313.For example, frequency offset estimation section 332 inputs a frequencyoffset estimation signal to radio sections 303 and 313, and radiosections 303 and 313 eliminate the received signal frequency offset.

Synchronization section 334 acquires time synchronization by means ofreceived quadrature baseband signal 304 and 314 FIG. 2 estimationsymbols, and outputs a timing signal 335 to Fourier transform section305 and Fourier transform section 315. That is to say, the receivingapparatus is able to establish time synchronization with thetransmitting apparatus by having synchronization section 334 detect FIG.2 estimation symbols 103 in received quadrature baseband signal 304 andreceived quadrature baseband signal 314.

Also, frequency offset estimation section 332 estimates frequency offsetfrom FIG. 2 estimation symbols 103 in parallel signals 306 and 316.

Signal processing section 321 separates channel A and channel Bmultiplexed signals for carrier 7 through carrier 12 in FIG. 2, andoutputs the resulting signals as channel A parallel signal 322 andchannel B parallel signal 323 respectively.

Demodulation section 324 demodulates carrier 7 through carrier 12channel A parallel signal 322, and demodulation section 326 demodulatescarrier 7 through carrier 12 channel B parallel signal 323.

Demodulation section 330 estimates channel distortion for selectedparallel signal 329 from FIG. 2 non-multiplexed carrier 1 throughcarrier 6 estimation symbols 103, and demodulates the carrier 1 throughcarrier 6 parallel signal from the estimated channel distortion.

At this time, received digital signals 325 and 327 obtained from carrier7 through carrier 12 channel A and channel B are of poor quality incomparison with carrier 1 through carrier 6 channel A received digitalsignal 331, but can be transmitted at high speed. Therefore, carrier 1through carrier 6 channel A received digital signal 331 is suitable fortransmission of important information and transmission of controlinformation.

Received digital signals 325 and 327 obtained from carrier 7 throughcarrier 12 channel A and channel B are input to a decoder X (not shown),and decoded. Then carrier 1 through carrier 6 channel A received digitalsignal 331 is input to a decoder Y (not shown), and decoded. By thismeans, different information X and Y can be obtained from differentdecoders X and Y, and although the information is the same in decoders Xand Y, it is possible to transmit information with different compressionratios.

It is possible to perform hierarchical transmission in which video istransmitted by means of carrier 1 through carrier 6 channel A receiveddigital signal 331 and difference information for Hi-Vision video istransmitted by received digital signals 325 and 327 obtained fromcarrier 7 through carrier 12 channel A and channel B.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, by creating frames whereby a plurality of modulatedsignals are transmitted from a plurality of antennas and frames wherebya modulated signal is transmitted from one antenna, and transmittingimportant information in a modulated signal transmitted from oneantenna, it is possible to secure data quality in a receiving apparatus.

Also, according to a transmitting apparatus and receiving apparatus ofthis embodiment, by transmitting different information in frames wherebya plurality of modulated signals are transmitted from a plurality ofantennas and frames whereby a modulated signal is transmitted from oneantenna, it is possible to transmit information of different quality andtransmission speed.

In FIG. 2, FIG. 3, and FIG. 4, the use of multiplex frames andnon-multiplexed frames with two channels and two antennas has beenillustrated as an example, but the present invention is not limited tothis. For example, it is possible to implement the present inventionsimilarly with multiplex frames using three channels and three antennas,multiplex frames using two channels and two of three antennas, andframes that cause the existence of non-multiplexed frames.

Also, the frame configurations are not limited to those in FIG. 2.Furthermore, an example has been described in which OFDM is used as thecommunication method, but it is possible to implement the presentinvention similarly as long as a multicarrier method is used. Moreover,a spread spectrum communication method may be used as the method foreach carrier in a multicarrier system. Thus, it is possible to implementthe present invention similarly with OFDM-CDM (Orthogonal FrequencyDivision Multiplexing-Code Division Multiplexing).

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Embodiment 2

In Embodiment 2 of the present invention, a description is given of acommunication method, transmitting apparatus, and receiving apparatuswhereby, when a multicarrier communication system is used in which abase station performs communication with a plurality of terminals,non-multiplexed carriers and multiplexed carriers are provided in basestation transmit frames, and a modulated signal is transmitted to aterminal using one or other of these types of carrier.

In this embodiment, signals are transmitted by the base stationapparatus shown in FIG. 3 using the frame configurations shown in FIG.2. FIG. 5 is a drawing showing an example of the arrangement of a basestation and terminals according to Embodiment 2 of the presentinvention. In FIG. 5, reference numeral 401 indicates a base station,reference numeral 402 indicates terminal A, reference numeral 403indicates terminal B, reference numeral 404 indicates terminal C,reference numeral 405 indicates terminal D, and reference numeral 406indicates the communication limit of base station 401 transmit signals.

When the locations of the base station and terminals are as shown inFIG. 5, the reception status of terminal A 402 and terminal B 403located far from base station 401 is poor, while the reception status ofterminal C 404 and terminal D 405 is good as they are near base station401.

Considering this, it is assumed that a base station equipped with atransmitting apparatus of this embodiment performs assignment tocommunication terminals in 3-carrier units as shown in FIG. 2, forexample.

In this case, in FIG. 15, carrier 7 through carrier 9 in FIG. 2 areassigned for communication with terminal C 404 and carrier 10 throughcarrier 12 in FIG. 2 are assigned for communication with terminal C 405,for both of which terminals the reception status is good, andcommunication is performed on channel A and channel B, so that thetransmission speed is high. Also, carrier 1 through carrier 3 in FIG. 2are assigned for communication with terminal A 402 and carrier 4 throughcarrier 6 in FIG. 2 are assigned for communication with terminal B 403,for both of which terminals the reception status is poor, andcommunication is performed on channel A, so that the transmission speedis low but received data quality is good.

At this time, by transmitting information concerning channel assignmentby means of control symbols 104 in FIG. 2, and having a terminaldemodulate control symbols 104, it is possible to ascertain where in aframe information for that terminal is assigned.

Next, the receiving apparatus side will be described. FIG. 6 is a blockdiagram showing an example of the configuration of a receiving apparatusof this embodiment. Parts in FIG. 6 identical to those in FIG. 4 areassigned the same reference numerals as in FIG. 4, and detaileddescriptions thereof are omitted.

A radio wave propagation environment estimation section 501 estimatesthe field strength, multipath environment, Doppler frequency, directionof arrival, channel fluctuation, interference intensity, polarized wavestate, and delay profile of received signals received by antenna 301 andantenna 311 from parallel signals 306 and 316, and outputs thisinformation as radio wave propagation environment information 502.

FIG. 7 is a block diagram showing an example of the configuration of atransmitting apparatus of this embodiment. An information generationsection 604 generates a transmit digital signal 605 from data 601 andradio wave propagation environment information 602 in accordance withrequest information 603 that a user or communication terminal considersnecessary, such as transmission speed, modulation method, and receiveddata quality, for example, and outputs transmit digital signal 605 to amodulated signal generation section 606.

Modulated signal generation section 606 modulates transmit digitalsignal 605, and outputs a transmit quadrature baseband signal 607 to aradio section 608.

Radio section 608 converts transmit quadrature baseband signal 607 toradio frequency and generates a modulated signal 609, which is output asa radio wave from an antenna 610.

The operation of the transmitting apparatus in FIG. 7 will now bedescribed. Radio wave propagation environment information 502 estimatedby radio wave propagation environment estimation section 501 of thereceiving apparatus in FIG. 6 corresponds to radio wave propagationenvironment information 602, and is input to information generationsection 604.

Information generation section 604 generates transmit digital signal 605from data 601, radio wave propagation environment information 602, andrequest information 603 that a user or communication terminal considersnecessary, such as transmission speed, modulation method, and receiveddata quality, for example. By this means, a terminal transmits a signalcontaining the radio wave propagation environment when the terminalreceives a modulated signal transmitted from the base station, andrequest information requested by the user or terminal.

Also, as a separate operation from this, information generation section604 determines and requests a communication method from requestinformation 603 comprising information the user or terminal considersnecessary, such as transmission speed, modulation method, and receiveddata quality, for example, and outputs transmit digital signal 605. Atthis time, information on the requested communication method is includedin transmit digital signal 605. Here, “communication method” isinformation as to whether communication is performed by means of amultiplex signal or whether communication is performed by means of anon-multiplexed signal.

FIG. 8 is a block diagram showing an example of the configuration of areceiving apparatus of this embodiment. In FIG. 8, a radio section 703converts a received signal 702 received by an antenna 701 to basebandfrequency, and outputs a received quadrature baseband signal 704 to ademodulation section 705.

Demodulation section 705 demodulates received quadrature baseband signal704 and outputs a received digital signal 706 to a method determinationsection 707.

Method determination section 707 extracts radio wave propagationenvironment information and request information contained in receiveddigital signal 706, selects the method whereby the base stationtransmits to a terminal—that is, either a method whereby signals of aplurality of channels are transmitted from a plurality of antennas, or amethod whereby signals of a plurality of channels are not multiplexedand a signal of one channel is transmitted—and outputs this as a controlsignal 708.

Next, the operation of the receiving apparatus in FIG. 8 will bedescribed. Method determination section 707 in FIG. 8 extracts radiowave propagation environment information and request informationcontained in a signal transmitted by the terminal A transmittingapparatus (FIG. 6), or extracts requested communication methodinformation, selects either a method whereby signals of a plurality ofchannels are transmitted from a plurality of antennas or a methodwhereby signals of a plurality of channels are not multiplexed and asignal of one channel is transmitted, and outputs this as control signal708.

Frame configuration signal generation section 221 in the base stationtransmitting apparatus in FIG. 3 has control signal 708 from a terminalA, terminal B, terminal C, or terminal D receiving apparatus as inputcontrol signal 223, and outputs frame configuration signal 222. By thismeans, modulated signals conforming to the frame configurations in FIG.2 can be transmitted by the base station transmitting apparatus.

A description will now be given of the means of setting thecommunication method at the start of communication when communication isperformed by an above-described transmitting apparatus and receivingapparatus.

Considering reception quality with respect to the radio wave propagationenvironment, the quality of carrier 1 through carrier 6 channel Ainformation symbols is good in comparison with carrier 7 through carrier12 channel A information symbols and channel B information symbols.

Therefore, when a terminal and base station start communicating, thebase station maintains data quality by transmitting information to theterminal in carrier 1 through carrier 6 channel A information symbols,thereby providing system stability.

Alternatively, when a terminal and base station start communicating, thebase station first transmits estimation symbols 103 as shown in FIG. 2to the terminal, the terminal receives the initially transmittedestimation symbols 103, estimates the radio wave propagationenvironment, and transmits radio wave propagation environment estimationinformation and request information.

Then, based on the radio wave propagation environment information andrequest information from the terminal, the base station selects eithertransmission of information by means of carrier 1 through carrier 6channel A information symbols or transmission of information by means ofcarrier 7 through carrier 12 channel A information symbols and channel Binformation symbols, and starts communication. By this means, dataquality can be maintained and therefore system stability is achieved.

Alternatively, when a terminal and base station start communicating, thebase station first transmits estimation symbols 103 as shown in FIG. 2to the terminal, the terminal receives the initially transmittedestimation symbols 103, estimates the radio wave propagationenvironment, takes radio wave propagation environment estimationinformation and request information into consideration, selects eithertransmission of information by means of carrier 1 through carrier 6channel A information symbols or transmission of information by means ofcarrier 7 through carrier 12 channel A information symbols and channel Binformation symbols, and makes a request to the base station.

Based on the request from the terminal, the base station selects eithertransmission of information by means of carrier 1 through carrier 6channel A information symbols or transmission of information by means ofcarrier 7 through carrier 12 channel A information symbols and channel Binformation symbols, and starts communication. By this means, dataquality can be maintained and therefore system stability is achieved.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, when a base station performs communication with aplurality of terminals, by assigning non-multiplexed carriers in basestation transmit frames in communication with a terminal whose receptionstatus is poor, and assigning multiplexed carriers in communication witha terminal whose reception quality is good, it is possible for aterminal to achieve compatibility between data transmission speed andreceived data quality.

In the above description, the use of multiplex frames andnon-multiplexed frames with two channels and two antennas has beenillustrated in FIG. 2, FIG. 3, and FIG. 4 as an example, but the presentinvention is not limited to this. For example, it is possible toimplement the present invention similarly with multiplex frames usingthree channels and three antennas, multiplex frames using two channelsand two of three antennas, and frames that cause the existence ofnon-multiplexed frames.

Also, the frame configurations are not limited to those in FIG. 2.Furthermore, an example has been described in which OFDM is used as thecommunication method, but it is possible to implement the presentinvention similarly as long as a multicarrier method is used. Moreover,a spread spectrum communication method may be used as the method foreach carrier in a multicarrier system. Thus, it is possible to implementthe present invention similarly with OFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Embodiment 3

In Embodiment 3 of the present invention, a description is given of atransmitting apparatus that transmits a frequency of a multiplexedmodulated signal and a frequency of a non-multiplexed modulated signalin a transmitting apparatus transmit frame, and a receiving apparatusthat can demodulate a modulated signal of either frequency.

FIG. 9 is a drawing showing communication signal frame configurationsaccording to Embodiment 3 of the present invention. FIG. 9 shows anexample of frame configurations on the frequency-time axes of basestation transmit signal channel A and channel B in frequency band f1according to this embodiment. In FIG. 9, the vertical axis indicatesfrequency and the horizontal axis indicates time. Reference numeral 102indicates an information symbol, reference numeral 103 indicates anestimation symbol, and reference numeral 104 indicates a control symbol.Estimation symbols 103 are pilot symbols for estimating timesynchronization, frequency synchronization, and distortion due to thechannel fluctuation, and control symbols 104 are symbols that transmitinformation used by a terminal for control, and are symbols fortransmitting information by means of information symbols 102.

Channel A and channel B signals are transmitted from two antennasrespectively. A transmitting apparatus of this embodiment transmits,separately from channel A and channel B signals, a channel C signal bymeans of an antenna separate from the channel A and channel B antennas.The channel C signal frame configuration is described below.

FIG. 10 is a drawing showing a communication signal frame configurationaccording to Embodiment 3 of the present invention. FIG. 10 shows anexample of a frame configuration on the frequency-time axes of basestation transmit signal channel C in frequency band f2 according to thisembodiment. In FIG. 10, the vertical axis indicates frequency and thehorizontal axis indicates time. Reference numeral 102 indicates aninformation symbol, reference numeral 103 indicates an estimationsymbol, and reference numeral 104 indicates a control symbol. Estimationsymbols 103 are pilot symbols for estimating time synchronization,frequency synchronization, and distortion due to the channelfluctuation, and control symbols 104 are symbols that transmitinformation used by a terminal for control, and are symbols fortransmitting information by means of information symbols 102.

A channel C signal is transmitted from an antenna separate from theantennas for channel A and channel B.

Also, a channel C signal is transmitted at a different frequency fromchannel A and channel B. FIG. 11 is a drawing showing the base stationtransmit signal frequency arrangement according to this embodiment. InFIG. 11, the vertical axis indicates power and the horizontal axisindicates frequency. Reference numeral 1001 indicates a channel A andchannel B multiplex transmit signal, with the frequency band designatedf1. Reference numeral 1002 indicates a channel C multiplex transmitsignal, with the frequency band designated f2. Thus, a channel C signalis transmitted at a different frequency from channel A and channel B.

In FIG. 11, carriers are arranged in frequency FIG. 1 and frequency f2,and frequency f1 is assigned for base station transmission, the frameconfigurations at this time being as shown in FIG. 9.

Frequency f2 is assigned for base station transmission, the frameconfiguration at this time being as shown in FIG. 10. At frequency f1,for example, channel A and channel B are transmitted and aremultiplexed, and the transmission speed is high but received dataquality is poor. At frequency f2, on the other hand, channel C istransmitted, and as there is no multiplexing, the transmission speed islow but received data quality is good.

A description will now be given of a transmitting apparatus thattransmits above-described channel A, channel B, and channel C signals.

FIG. 12 is a block diagram showing an example of the configuration of atransmitting apparatus of a base station according to this embodiment.Parts in FIG. 12 identical to those in FIG. 3 are assigned the samereference numerals as in FIG. 3, and detailed descriptions thereof areomitted.

In FIG. 12, a serial/parallel conversion section 1102 generates parallelsignal 1103 from a channel C transmit digital signal 1101 in accordancewith frame configuration signal 222.

An inverse discrete Fourier transform section 1104 performs inverseFourier transform processing of channel C parallel signal 1103, andoutputs a post-inverse-Fourier-transform signal 1105 resulting from to aradio section 1106.

Radio section 1106 converts channel C post-inverse-Fourier-transformsignal 1105 to radio frequency, and outputs a channel C transmit signal1107 to a power amplification section 1108.

Power amplification section 1108 amplifies channel C transmit signal1107, and an amplified C transmit signal 1109 is output as a radio wavefrom a channel C antenna 1110.

The operation of the transmitting apparatus in FIG. 12 will now bedescribed.

Channel A serial/parallel conversion section 202 generates channel Aparallel signal 203 in which information symbols, control symbols, andestimation symbols are present, in accordance with the channel A frameconfiguration in FIG. 9, based on channel A transmit digital signal 201and frame configuration signal 222.

Channel B serial/parallel conversion section 212 generates channel Bparallel signal 213 in which information symbols, control symbols, andestimation symbols are present, in accordance with the channel B frameconfiguration in FIG. 9, based on channel B transmit digital signal 211and frame configuration signal 222.

Channel A and channel B signals are then transmitted at frequency f1.

Estimation symbols 103 in FIG. 9 are inserted for time synchronizationand frequency offset estimation. They are also signals for performingchannel estimation for separating channel A and channel B signals.

Channel C serial/parallel conversion section 1102 receives a channel Ctransmit digital signal 1101 and channel C frame configuration signal222 as input and generates channel C parallel signal 1103 in whichinformation symbols, control symbols, and estimation symbols arepresent, in accordance with the channel C frame configuration in FIG.10.

A channel C signal is then transmitted at frequency f2.

Estimation symbols 103 in FIG. 10 are inserted for time synchronizationand frequency offset estimation.

When channel A information symbols and channel A and channel Binformation symbols are compared with channel C information symbols, inthe receiving apparatus they are of better quality than channel Cinformation symbols. Considering this fact, it is appropriate forinformation of high importance to be transmitted in channel Cinformation symbols.

It is possible to transmit one kind of information medium in channel C,and transmit one kind of information medium in channel A and channel B,such as transmitting video information, for example, using channel Cinformation symbols, and transmitting Hi-Vision video using channel Aand channel B information symbols. Also, the same kind of informationmedium may by transmitted in channel C transmission and channel A andchannel B transmission. At this time, the compression ratio when coding,for example, will be different for the same kind of information.

It is also possible to transmit information in a hierarchical fashion,with a certain kind of information transmitted by means of channel Cinformation symbols, and difference information transmitted usingchannel A and channel B information symbols.

FIG. 13 is a block diagram showing the configuration of a receivingapparatus of a terminal according to this embodiment. In FIG. 13, aradio section 1203 converts a frequency band f1 received signal 1202received by an antenna 1201 to baseband frequency, and outputs areceived quadrature baseband signal 1204 to a Fourier transform section1205 and synchronization section 1230.

Fourier transform section 1205 performs Fourier transform processing onreceived quadrature baseband signal 1204, and outputs resulting parallelsignal 1206 to a channel distortion estimation section 1207, channeldistortion estimation section 1209, signal processing section 1221, andfrequency offset estimation section 1228.

Channel distortion estimation section 1207 estimates channel A channeldistortion from parallel signal 1206 estimation symbols, and outputs achannel A channel distortion parallel signal 1208 to signal processingsection 1221.

Channel distortion estimation section 1209 estimates channel B channeldistortion from parallel signal 1206 estimation symbols, and outputs achannel B channel distortion parallel signal 1210 to signal processingsection 1221.

A radio section 1213 converts a received signal 1212 received by anantenna 1211 to baseband frequency, and outputs a received quadraturebaseband signal 1214 to a Fourier transform section 1215 andsynchronization section 1230.

Fourier transform section 1215 performs Fourier transform processing onreceived quadrature baseband signal 1214, and outputs resulting parallelsignal 1216 to a channel distortion estimation section 1217, channeldistortion estimation section 1219, signal processing section 1221, andfrequency offset estimation section 1228.

Channel distortion estimation section 1217 estimates channel A channeldistortion from parallel signal 1216 estimation symbols, and outputs achannel A channel distortion parallel signal 1218 to signal processingsection 1221.

Channel distortion estimation section 1219 estimates channel B channeldistortion from parallel signal 1216 estimation symbols, and outputs achannel B channel distortion parallel signal 1220 to signal processingsection 1221.

Signal processing section 1221 separates parallel signals 1206 and 1216into channel A and channel B signals based on channel A channeldistortion parallel signals 1208 and 1218, and channel B channeldistortion parallel signals 1210 and 1220. Of the separated signals,signal processing section 1221 then outputs channel A parallel signal1222 to a demodulation section 1224, and outputs channel B parallelsignal 1223 to a demodulation section 1226.

Demodulation section 1224 demodulates channel A parallel signal 1222,and outputs a received digital signal 1225.

Demodulation section 1226 demodulates channel B parallel signal 1223,and outputs a received digital signal 1227.

Frequency offset estimation section 1228 estimates the frequency offsetamount from parallel signal 1206 and 1216 (FIG. 9), and outputs afrequency offset estimation signal 1229. Specifically, frequency offsetestimation section 1228 estimates the frequency offset amount fromestimation symbols 103 in FIG. 9. Then frequency offset estimationsection 1228 outputs a frequency offset estimation signal to radiosections 1203 and 1213, for example, and radio sections 1203 and 1213eliminate the received signal frequency offset.

Synchronization section 1230 acquires time synchronization usingreceived quadrature baseband signals 1204 and 1214, and outputs a timingsignal 1231 to Fourier transform section 1205 and Fourier transformsection 1215. Synchronization section 1230 acquires time synchronizationby means of estimation symbols 103 in FIG. 9, for example.

A radio section 1234 converts a frequency band f2 received signal 1233received by an antenna 1232 to baseband frequency, and outputs areceived quadrature baseband signal 1235 to a Fourier transform section1236 and synchronization section 1244.

Fourier transform section 1236 performs Fourier transform processing onreceived quadrature baseband signal 1235, and outputs resulting parallelsignal 1237 to a channel distortion estimation section 1238,demodulation section 1240, and frequency offset estimation section 1242.

Channel distortion estimation section 1238 estimates channel distortionfrom parallel signal 1237, and outputs a channel distortion parallelsignal 1239 to demodulation section 1240.

Based on channel distortion parallel signal 1239, demodulation section1240 eliminates channel distortion from channel C parallel signal 1237,demodulates the signal, and outputs a channel C received digital signal1241.

Next, the operation of the receiving apparatus in FIG. 13 will bedescribed.

Synchronization section 1230 detects FIG. 9 estimation symbols 103 inreceived quadrature baseband signal 1204 and received quadraturebaseband signal 1214, and the receiving apparatus establishes timesynchronization with the transmitting apparatus.

Frequency offset estimation section 1228 estimates frequency offset fromFIG. 9 estimation symbols 103 in parallel signals 1206 and 1216.

Signal processing section 1221 separates FIG. 9 multiplexed signals intoa channel A signal and channel B signal.

Synchronization section 1244 acquires time synchronization receivedquadrature baseband signal 1235 based on FIG. 10 estimation symbols.

Frequency offset estimation section 1242 estimates frequency offset ofparallel signals 1237 based on FIG. 10 estimation symbols.

Channel distortion estimation section 1238 estimates channel distortionof parallel signal 1237 based on FIG. 10 estimation symbols.

Channel C demodulation section 1240 has channel distortion parallelsignal 1239 as input, and demodulates FIG. 10 parallel signal 1237information symbols.

At this time, received digital signals 1225 and 1227 obtained fromchannel A and channel B are of poor quality in comparison with channel Creceived digital signal 1241, but can be transmitted at high speed.Considering this fact, channel C received digital signal 1241 issuitable for transmission of important information and transmission ofcontrol information.

Received digital signals 1225 and 1227 obtained from channel A andchannel B are input to a decoder X (not shown), and decoded. Thenchannel C received digital signal 1241 is input to a decoder Y (notshown), and decoded. By this means, different information X and Y can beobtained from different decoders X and Y, and although the informationis the same in decoders X and Y, it is possible to transmit informationwith different compression ratios.

It is possible to perform hierarchical transmission in which video istransmitted by means of channel C received digital signal 1241 anddifference information for Hi-Vision video is transmitted by receiveddigital signals 1225 and 1227 obtained from channel A and channel B.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, there is a frequency for transmitting a plurality ofmodulated signals from a plurality of antennas and a frequency fortransmitting a modulated signal from one antenna, and by transmittingimportant information in a modulated signal transmitted from oneantenna, it is possible to secure data quality in a receiving apparatus.

Also, according to a transmitting apparatus and receiving apparatus ofthis embodiment, by transmitting different information at a frequencyfor transmitting a plurality of modulated signals from a plurality ofantennas and a frequency for transmitting a modulated signal from oneantenna, it is possible to transmit information of different quality andtransmission speed.

In FIG. 9, the use of multiplex frames on two channels is illustrated,but the present invention is not limited to this. Also, in FIG. 11, anexample with two frequency bands is illustrated, but the presentinvention is not limited to this. For example, it is possible for thereto be three frequency bands, and for frequencies to be assigned for3-channel multiplex transmission, 2-channel multiplex transmission, andsingle-channel transmission.

A description has been given above that refers to a configuration withtwo antennas transmitting two channels and one antenna transmitting onechannel in the transmitting apparatus in FIG. 12, but the presentinvention is not limited to this. For example, the transmittingapparatus may be equipped with two or more antennas for transmitting twochannels.

Also, in the case where there are three frequency bands, and frequenciesare assigned for 3-channel multiplex transmission, 2-channel multiplextransmission, and single-channel transmission, the transmittingapparatus may be equipped with a plurality of antennas for 3-channelmultiplex transmission, or may be equipped with a plurality of antennasfor 2-channel multiplex transmission, or may be equipped with aplurality of antennas for single-channel transmission. The same appliesto the receiving apparatus in FIG. 13.

Furthermore, an example has been described in which OFDM is used as thecommunication method, but it is possible to implement the presentinvention similarly as long as a multicarrier method is used. Moreover,a spread spectrum communication method may be used as the method foreach carrier in a multicarrier system. Thus, it is possible to implementthe present invention similarly with OFDM-CDM (Orthogonal FrequencyDivision Multiplexing-Code Division Multiplexing).

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Embodiment 4

In Embodiment 4 of the present invention, a description is given of acommunication method, transmitting apparatus, and receiving apparatuswhereby, when a base station performs communication with a plurality ofterminals, a frequency of a multiplexed modulated signal and a frequencyof a non-multiplexed modulated signal are provided in transmit frames,and a modulated signal is transmitted to a terminal using one or otherof these frequencies.

FIG. 14 is drawing showing an example of the configuration of areceiving apparatus of a terminal according to Embodiment 4 of thepresent invention. Parts in FIG. 14 identical to those in FIG. 13 areassigned the same reference numerals as in FIG. 13, and detaileddescriptions thereof are omitted. The receiving apparatus in FIG. 14differs from the receiving apparatus in FIG. 13 in that a radio wavepropagation environment estimation section 1301 and radio wavepropagation environment estimation section 1303 are provided, afrequency in the base station is used as assignment information, and thepropagation environment is estimated by the receiving apparatus.

Radio wave propagation environment estimation section 1301 estimates theradio wave propagation environments of received signals received byantenna 1201 and antenna 1211, respectively, from parallel signals 1206and 1216, and outputs radio wave propagation environment estimationinformation 1302.

Radio wave propagation environment estimation section 1303 estimates theradio wave propagation environment of a received signals received byantenna 1232 from parallel signal 1237, and outputs radio wavepropagation environment estimation information 1304.

FIG. 15 is a drawing showing an example of the configuration of atransmitting apparatus of a base station according to this embodiment.Parts in FIG. 15 identical to those in FIG. 6 are assigned the samereference numerals as in FIG. 6, and detailed descriptions thereof areomitted. The transmitting apparatus in FIG. 15 differs from thetransmitting apparatus in FIG. 6 in that an information generationsection 604 is provided, and based on a propagation environmentestimated by the receiving apparatus, a frequency not multiplexed by thebase station is assigned to communication with a terminal whosereception status is poor, and a frequency multiplexed by the basestation is assigned to communication with a terminal whose receptionstatus is good.

Information generation section 604 generates transmit digital signal 605from data signal 601, radio wave propagation environment estimationinformation 1401 and 1402, and request information 603, and outputs thistransmit digital signal 605 to modulated signal generation section 606.

It is assumed that the locations of the base station and terminals areas shown in FIG. 5. At this time, the reception status of terminal A 402and terminal B 403 located far from base station 401 is poor, while thereception status of terminal C 404 and terminal D 405 is good as theyare near base station 401. Considering this, for example, as shown inFIG. 9, assignment is performed for communication terminals with regardto time-unit or frequency-unit. For example, time 3 through time 6 areassigned for communication with terminal C and time 7 through time 10are assigned for communication with terminal D. Alternatively, carrier 1through carrier 3 are assigned for communication with terminal C andcarrier 4 through carrier 6 are assigned for communication with terminalD. At this time, communication is performed on channel A and channel B,so that the transmission speed is high.

Then, assignment is performed for terminal A 402 and terminal B 403 forboth of which the reception status is poor, with regard to time-unit orfrequency-unit, as shown in FIG. 10. For example, time 3 through time 6are assigned for communication with terminal A, and time 7 through time10 are assigned for communication with terminal B. Alternatively,carrier 1 through carrier 3 are assigned for communication with terminalA and carrier 4 through carrier 6 are assigned for communication withterminal B. At this time, communication is performed on channel C, sothat the transmission speed is low but received data quality is good.

Also, as shown in FIG. 11, the multiplexed signal of channel A andchannel B in FIG. 9 is transmitted at frequency f1, and the multiplexedsignal of channel C in FIG. 10 is transmitted at frequency f2.

The base station apparatus transmits information concerning channelassignment by means of control symbols 104 in FIG. 9 and FIG. 10, and aterminal can ascertain where in a frame information for that terminal isassigned by demodulating control symbols 104.

The operation of the receiving apparatus and transmitting apparatus of aterminal will now be described in detail.

In FIG. 14, radio wave propagation environment estimation section 1301has parallel signals 1206 and 1216 as input, and estimates the fieldstrength, multipath environment, Doppler frequency, direction ofarrival, channel fluctuation, interference intensity, polarized wavestate, and delay profile of a signal received by antenna 1201 and asignal received by antenna 1211 from estimation symbols 103 in FIG. 9,for example.

Radio wave propagation environment estimation section 1303 estimates thefield strength, multipath environment, Doppler frequency, direction ofarrival, channel fluctuation, interference intensity, polarized wavestate, and delay profile of a signal received by antenna 1232 aboutparallel signal 1237 based on FIG. 10 estimation symbols.

Using radio wave propagation environment estimation information 1302 andradio wave propagation environment estimation information 1304 estimatedby the receiving apparatus, the transmitting apparatus in FIG. 15determines assignment of a non-multiplexed frequency or assignment of abase station multiplexed frequency. Radio wave propagation environmentestimation information 1302 estimated by radio wave propagationenvironment estimation section 1301 of the receiving apparatus in FIG.14 corresponds to radio wave propagation environment information 1401,and radio wave propagation environment estimation information 1304estimated by radio wave propagation environment estimation section 1303corresponds to radio wave propagation environment information 1402, andradio wave propagation environment information 1401 and radio wavepropagation environment information 1402 are input to informationgeneration section 604.

Information generation section 604 generates transmit digital signal 605from data 601, radio wave propagation environment estimation information1401 and 1402, and request information 603 that a user or communicationterminal considers necessary, such as transmission speed, modulationmethod, and received data quality, for example. By this means, aterminal transmits a signal containing the radio wave propagationenvironment when the terminal receives a modulated signal transmittedfrom the base station, and request information requested by the user orterminal.

Also, information generation section 604 has data 601, radio wavepropagation environment information 602, and request information 603that a user or communication terminal considers necessary, such astransmission speed, modulation method, and received data quality, asinput, and determines and requests a communication method from radiowave propagation environment estimation information 1401 and 1402 andrequest information 603. At this time, information on the requestedcommunication method is included in transmit digital signal 605. Here,“communication method” is information as to whether communication isperformed by means of a multiplex signal and frequency f1 or whethercommunication is performed by means of a non-multiplexed signal andfrequency f2.

Using this communication method information, the base station apparatusdecides whether to perform communication with a multiplex signal andfrequency f1 or whether to transmit a signal using a non-multiplexedsignal and frequency f2.

For example, in the base station in FIG. 8, method determination section707 extracts radio wave propagation environment information and requestinformation contained in a signal transmitted by the terminal Atransmitting apparatus (FIG. 15), or extracts requested communicationmethod information. Then, based on this communication methodinformation, method determination section 707 selects the frequency f1method whereby signals of a plurality of channels are transmitted from aplurality of antennas, or the frequency f2 method whereby signals of aplurality of channels are not multiplexed and a signal of one channel istransmitted, and outputs this as control signal 708.

Frame configuration signal generation section 221 in the base stationtransmitting apparatus in FIG. 12 performs frame configuration withcontrol signal 708 in FIG. 8 from the receiving apparatus for a terminal(for example, terminal A, terminal B, terminal C, or terminal D in FIG.5) as input control signal 223, and outputs frame configuration signal222. By this means, modulated signals conforming to the frameconfigurations in FIG. 9 and FIG. 10 can be transmitted by the basestation transmitting apparatus.

A description will now be given of the means of setting thecommunication method at the start of communication.

Considering reception quality with respect to the radio wave propagationenvironment, the quality of channel C information symbols is good incomparison with channel A information symbols and channel B informationsymbols.

Therefore, when a terminal and base station start communicating, thebase station maintains data quality by transmitting information to theterminal in channel C information symbols, thereby providing systemstability.

Alternatively, when a terminal and base station start communicating, thebase station first transmits estimation symbols 103 as shown in theframe configuration in FIG. 9 and FIG. 10 to the terminal. The terminalthen receives the initially transmitted estimation symbols 103,estimates the radio wave propagation environment, and transmits radiowave propagation environment estimation information and requestinformation. Then, based on the radio wave propagation environmentinformation and request information from the terminal, the base stationselects either transmission of information by means of channel Cinformation symbols or transmission of information by means of channel Ainformation symbols and channel B information symbols, and startscommunication. By this means, data quality can be maintained andtherefore system stability is achieved.

Alternatively, when a terminal and base station start communicating, thebase station first transmits estimation symbols 103 as shown in FIG. 9and FIG. 10 to the terminal, the terminal receives the initiallytransmitted estimation symbols 103, estimates the radio wave propagationenvironment, takes radio wave propagation environment estimationinformation and request information into consideration, selects eithertransmission of information by means of channel C information symbols ortransmission of information by means of channel A information symbolsand channel B information symbols, and makes a request to the basestation. Based on the request from the terminal, the base stationselects either transmission of information by means of channel Cinformation symbols or transmission of information by means of channel Ainformation symbols and channel B information symbols, and startscommunication. By this means, data quality can be maintained andtherefore system stability is achieved.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, when a base station performs communication with aplurality of terminals, by assigning a non-multiplexed frequency in basestation transmit frames in communication with a terminal whose receptionstatus is poor, and assigning a multiplexed frequency in communicationwith a terminal whose reception quality is good, it is possible for aterminal to achieve compatibility between data transmission speed andreceived data quality.

In FIG. 9, the use of multiplex frames on two channels is illustrated,but the present invention is not limited to this. Also, in FIG. 11, anexample with two frequency bands is illustrated, but the presentinvention is not limited to this. For example, it is possible for thereto be three frequency bands, and for frequencies to be assigned for3-channel multiplex transmission, 2-channel multiplex transmission, andsingle-channel transmission. A description has been given above thatrefers to a configuration with two antennas transmitting two channelsand one antenna transmitting one channel in the transmitting apparatusin FIG. 12, but the present invention is not limited to this, and two ormore antennas may be provided for transmitting two channels. Also, inthe case where there are three frequency bands, and frequencies areassigned for 3-channel multiplex transmission, 2-channel multiplextransmission, and single-channel transmission, it is also possible toprovide a plurality of antennas for 3-channel multiplex transmission, toprovide a plurality of antennas for 2-channel multiplex transmission,and to provide a plurality of antennas for single-channel transmission.The same applies to the receiving apparatus in FIG. 14. Furthermore, anexample has been described in which OFDM is used as the communicationmethod, but it is possible to implement the present invention similarlywith either a multicarrier method or a single-carrier method. Moreover,a spread spectrum communication method may be used as the method foreach carrier in a multicarrier system. Thus, it is possible to implementthe present invention similarly with OFDM-CDM (Orthogonal FrequencyDivision Multiplexing-Code Division Multiplexing).

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Embodiment 5

In Embodiment 5 of the present invention, a description is given of atransmitting apparatus that transmits a non-multiplexed time modulatedsignal and a multiplexed time modulated signal in transmit frames, and areceiving apparatus that can demodulate a modulated signal of eithertime.

FIG. 16 is a drawing showing an example of the frame configuration onthe frequency-time axes of channel A and channel B according to thisembodiment. In FIG. 16, the vertical axis indicates frequency and thehorizontal axis indicates time. Reference numeral 101 indicates a guardsymbol, reference numeral 102 indicates an information symbol, referencenumeral 103 indicates an estimation symbol, and reference numeral 104indicates a control symbol. Here, guard symbols 101 are symbols forwhich there is no modulated signal, estimation symbols 103 are pilotsymbols for estimating time synchronization, frequency synchronization,and distortion due to the channel fluctuation, and control symbols 104are symbols that transmit information used by a terminal for control,and are symbols for transmitting information by means of informationsymbols 102.

In time 3 through time 10, channel A information symbols and channel Binformation symbols are transmitted, and in time 11 through time 18,only channel A information symbols are transmitted.

The operation of this transmitting apparatus will now be described.

Serial/parallel conversion section 202 takes channel A transmit digitalsignal 201 and configures a frame in which information symbols, controlsymbols, and estimation symbols are present, as in the channel A frameconfiguration in FIG. 16, in accordance with frame configuration signal222.

Serial/parallel conversion section 212 takes channel B transmit digitalsignal 211 and outputs channel B parallel signal 213 with time 1estimation symbols 102 and time 3 through 10 information symbols 102according to the channel B frame configuration in FIG. 16, in accordancewith frame configuration signal 222.

Estimation symbols 103 are inserted for time synchronization andfrequency offset estimation. They are also used for signal separation inframes in which channel A and channel B symbols are multiplexed.

When time 11 through 18 channel A information symbols and time 3 through10 channel A and channel B information symbols are compared, in thereceiving apparatus time 11 through 18 channel A information symbols areof better quality than time 3 through 10 channel A and channel Binformation symbols. Considering this fact, it is appropriate forinformation of high importance to be transmitted in time 11 through 18channel A information symbols.

It is possible to transmit one kind of information medium in time 11through 18 channel A information symbols, and transmit one kind ofinformation medium in time 3 through 10 channel A and channel Binformation symbols, such as transmitting video information, forexample, using time 11 through 18 channel A information symbols, andtransmitting Hi-Vision video using time 3 through 10 channel A andchannel B information symbols. Also, the same kind of information mediummay by transmitted in time 11 through 18 channel A information symboltransmission and time 3 through 10 channel A and channel B informationsymbol transmission. At this time, the compression ratio when coding,for example, will be different for the same kind of information.

It is also possible to transmit information in a hierarchical fashion,with a certain kind of information transmitted by means of time 11through 18 channel A information symbols, and difference informationtransmitted using time 3 through 10 channel A and channel B informationsymbols.

A transmitting apparatus of this embodiment generates and transmitssignals with the frame configurations shown in FIG. 16 using theconfiguration in FIG. 3. FIG. 17 is a drawing showing an example of theconfiguration of a receiving apparatus according to Embodiment 5 of thepresent invention. Parts in FIG. 17 identical to those in FIG. 4 areassigned the same reference numerals as in FIG. 4, and detaileddescriptions thereof are omitted.

Signal processing section 321 separates parallel signals 306 and 316into multiplexed time channel A parallel signal 1601 and channel Bparallel signal 1604 based on channel A channel distortion parallelsignals 308 and 318, and channel B channel distortion parallel signals310 and 320, outputs parallel signal 1601 to a demodulation section1602, and outputs parallel signal 1604 to a demodulation section 1605.

Demodulation section 1602 demodulates separated channel A parallelsignal 1601, and outputs a channel A received digital signal 1603.

Demodulation section 1605 demodulates separated channel B parallelsignal 1604, and outputs a channel B received digital signal 1606.

Of parallel signals 306 and 316, selection section 328 selects theparallel signal with the greater field strength, for example, of thetimes of a channel A signal only in FIG. 2, and outputs a selectedparallel signal 1607 to a demodulation section 1608.

Demodulation section 1608 demodulates selected parallel signal 1607, andoutputs a channel A received digital signal 1609.

The operation of a transmitting apparatus and receiving apparatusaccording to this embodiment will now be described in detail using FIG.3, FIG. 16, and FIG. 17.

The operation of the receiving apparatus is described below.

The receiving apparatus is able to establish time synchronization withthe transmitting apparatus by having synchronization section 334 detectFIG. 16 estimation symbols 103 in received quadrature baseband signal304 and received quadrature baseband signal 314.

Frequency offset estimation section 332 can estimate the frequencyoffset from FIG. 16 estimation symbols 103 in parallel signal 306 and316.

Signal processing section 321 separates time 3 through 10 channel A andchannel B information symbol multiplexed signals in FIG. 16 into a time3 through 10 channel A signal and a time 3 through 10 channel B signal,and outputs the resulting signals as channel A parallel signal 1601 andchannel B parallel signal 1604 respectively.

Channel A demodulation section 1602 has channel A parallel signal 1601as input, and outputs channel A received digital signal 1603. Channel Bdemodulation section 1605 has channel B parallel signal 1604 as input,and outputs channel B received digital signal 1606.

Channel A demodulation section 1608 has selected parallel signal 1607 asinput, estimates channel distortion from FIG. 16 estimation symbols 103,demodulates the time 11 through 18 channel A parallel signal from theestimated channel distortion, and outputs received digital signal 1609.

At this time, received digital signals 1603 and 1606 obtained fromchannel A and channel B are of poor quality in comparison with channel Areceived digital signal 1609, but can be transmitted at high speed.Considering this fact, channel A received digital signal 1609 issuitable for transmission of important information and transmission ofcontrol information. Received digital signals 1603 and 1606 obtainedfrom channel A and channel B are input to a decoder X (not shown), anddecoded. Then channel A received digital signal 1609 is input to adecoder Y (not shown), and decoded. By this means, different informationX and Y can be obtained from different decoders X and Y, and althoughthe information is the same in decoders X and Y, it is possible totransmit information with different compression ratios.

It is possible to perform hierarchical transmission in which video istransmitted by means of channel A received digital signal 1609 anddifference information for Hi-Vision video is transmitted by receiveddigital signals 1603 and 1606 obtained from channel A and channel B.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, by having frames whereby a plurality of modulatedsignals are transmitted from a plurality of antennas and frames wherebya modulated signal is transmitted from one antenna, and transmittingimportant information in a modulated signal transmitted from oneantenna, it is possible to secure data quality in a receiving apparatus.

Also, according to a transmitting apparatus and receiving apparatus ofthis embodiment, by transmitting different information in frames wherebya plurality of modulated signals are transmitted from a plurality ofantennas and frames whereby a modulated signal is transmitted from oneantenna, it is possible to transmit information of different quality andtransmission speed.

In FIG. 3, FIG. 16, and FIG. 17, the use of multiplex frames andnon-multiplexed frames with two channels and two antennas has beenillustrated as an example, but the present invention is not limited tothis. For example, it is possible to implement the present inventionsimilarly with multiplex frames using three channels and three antennas,multiplex frames using two channels and two of three antennas, andframes that cause the existence of non-multiplexed frames.

Also, the frame configurations are not limited to those in FIG. 2.Furthermore, an example has been described in which OFDM is used as thecommunication method, but it is possible to implement the presentinvention similarly with either a multicarrier method or asingle-carrier method. Moreover, a spread spectrum communication methodmay be used as the method for each carrier in a multicarrier system.Thus, it is possible to implement the present invention similarly withOFDM-CDM (Orthogonal Frequency Division Multiplexing-Code DivisionMultiplexing).

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Embodiment 6

In Embodiment 6 of the present invention, a description is given of acommunication method, transmitting apparatus, and receiving apparatuswhereby, when a base station performs communication with a plurality ofterminals, non-multiplexed frames and multiplexed frames are provided inbase station transmit frames, and a modulated signal is transmitted to aterminal using one or other of these types of frame.

FIG. 18 is a block diagram showing an example of the configuration of areceiving apparatus of a terminal according to Embodiment 6 of thepresent invention. Parts in FIG. 18 identical to those in FIG. 4 or FIG.17 are assigned the same reference numerals as in FIG. 4 or FIG. 17, anddetailed descriptions thereof are omitted.

A radio wave propagation environment estimation section 1701 estimatesthe field strength, multipath environment, Doppler frequency, directionof arrival, channel fluctuation, interference intensity, polarized wavestate, and delay profile of received signals received by antenna 301 andantenna 311 from parallel signals 306 and 316, and outputs thisinformation as radio wave propagation environment information 1702.

It is assumed that the locations of the base station and terminals areas shown in FIG. 5. At this time, the reception status of terminal A 402and terminal B 403 located far from base station 401 is poor, while thereception status of terminal C 404 and terminal D 405 is good as theyare near base station 401. Considering this, it is assumed thatassignment is performed to communication terminals as shown in FIG. 16in time-unit or frequency-unit, for example. For example, in channel Aand channel B, time 3 through time 6 are assigned for communication withterminal C and time 7 through time 10 are assigned for communicationwith terminal D. Alternatively, in channel A and channel B, carrier 1through carrier 3 are assigned for communication with terminal C andcarrier 4 through carrier 6 are assigned for communication with terminalD. At this time, communication is performed on channel A and channel B,so that the transmission speed is high.

Then, assignment is performed to terminal A 402 and terminal B 403, forwhich the reception status is poor, as shown in FIG. 16 in time-unit orfrequency-unit. For example, in channel A, time 11 through time 14 areassigned for communication with terminal A and time 15 through time 18are assigned for communication with terminal B. Alternatively, inchannel A, carrier 1 through carrier 3 are assigned for communicationwith terminal A and carrier 4 through carrier 6 are assigned forcommunication with terminal B. At this time, communication is performedon only channel A, so that the transmission speed is low but receiveddata quality is good.

At this time, by transmitting information concerning channel assignmentby means of control symbols 104 in FIG. 16, and having a terminaldemodulate control symbols 104, it is possible to ascertain where in aframe information for that terminal is assigned.

Next, the receiving apparatus and the transmitting apparatus of theterminal are explained in detail.

FIG. 18 shows one example of the configuration of the receivingapparatus of the terminal. A radio wave propagation environmentestimation section 1701 receives parallel signals 306 and 316 as input,estimates the field strength, multipath environment, Doppler frequency,direction of arrival, channel fluctuation, interference intensity,polarized wave state, and delay profile of received signals received byantenna 301 and of received signals received by antenna 311 by means ofestimation symbols 103 in FIG. 16, and outputs this information as radiowave propagation environment information 1702.

Radio wave propagation environment information 1702 estimated by radiowave propagation environment estimation section 1701 of the receivingapparatus in FIG. 18 corresponds to radio wave propagation environmentinformation 602 in FIG. 6, and is input to information generationsection 604.

Information generation section 604 generates transmit digital signal 605from data 601, radio wave propagation environment information 602, andrequest information 603 that a user or communication terminal considersnecessary, such as transmission speed, modulation method, and receiveddata quality, for example. By this means, a terminal transmits a signalcontaining the radio wave propagation environment when the terminalreceives a modulated signal transmitted from the base station, andrequest information requested by the user or terminal.

Also, information generation section 604 has data 601, radio wavepropagation environment information 602, and request information 603that a user or communication terminal considers necessary, such astransmission speed, modulation method, and received data quality, asinput, determines and requests a communication method from radio wavepropagation environment information 602 and request information 603, andoutputs transmit digital signal 605. At this time, information on therequested communication method is included in transmit digital signal605. Here, “communication method” is information as to whethercommunication is performed by means of a multiplex signal or whethercommunication is performed by means of a non-multiplexed signal.

A description will now be given of the means of setting thecommunication method at the start of communication.

In FIG. 16, considering reception quality with respect to the radio wavepropagation environment, the quality of time 11 through 18 channel Ainformation symbols is good in comparison with time 3 through 10 channelA information symbols and channel B information symbols.

Therefore, when a terminal and base station start communicating, thebase station maintains data quality by transmitting information to theterminal in time 11 through 18 channel A information symbols, therebyproviding system stability.

Alternatively, when a terminal and base station start communicating, thebase station first transmits estimation symbols 103 as shown in FIG. 16to the terminal, the terminal receives the initially transmittedestimation symbols 103, estimates the radio wave propagationenvironment, and transmits radio wave propagation environment estimationinformation and request information. Then, based on the radio wavepropagation environment information and request information from theterminal, the base station selects either transmission of information bymeans of time 11 through 18 channel A information symbols ortransmission of information by means of time 3 through 10 channel Ainformation symbols and channel B information symbols, and startscommunication. By this means, data quality can be maintained andtherefore system stability is achieved.

Alternatively, when a terminal and base station start communicating, thebase station first transmits estimation symbols 103 as shown in FIG. 9and FIG. 10 to the terminal, the terminal receives the initiallytransmitted estimation symbols 103, estimates the radio wave propagationenvironment, takes radio wave propagation environment estimationinformation and request information into consideration, selects eithertransmission of information by means of time 11 through 18 channel Ainformation symbols or transmission of information by means of time 3through 10 channel A information symbols and channel B informationsymbols, and makes a request to the base station.

Based on the request from the terminal, the base station selects eithertransmission of information by means of time 11 through 18 channel Ainformation symbols or transmission of information by means of time 3through 10 channel A information symbols and channel B informationsymbols, and starts communication. By this means, data quality can bemaintained and therefore system stability is achieved.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, when a base station performs communication with aplurality of terminals, by assigning a non-multiplexed frame in basestation transmit frames in communication with a terminal whose receptionstatus is poor, and assigning a multiplexed frame in communication witha terminal whose reception quality is good, it is possible for aterminal to achieve compatibility between data transmission speed andreceived data quality.

In FIG. 3, FIG. 16, and FIG. 18, the use of multiplex frames andnon-multiplexed frames with two channels and two antennas has beenillustrated as an example, but the present invention is not limited tothis. For example, it is possible to implement the present inventionsimilarly with multiplex frames using three channels and three antennas,multiplex frames using two channels and two of three antennas, andframes that cause the existence of non-multiplexed frames. Also, theframe configurations are not limited to those in FIG. 2. Furthermore, anexample has been described in which OFDM is used as the communicationmethod, but it is possible to implement the present invention similarlywith a multicarrier method with regard to time-unit and frequency-unitassignment, or a single-carrier method with regard to time-unitassignment. Moreover, a spread spectrum communication method may be usedas the method for each carrier in a multicarrier system. Thus, it ispossible to implement the present invention similarly with OFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Embodiment 7

In Embodiment 7 of the present invention, a description is given ofcoding and pilot symbol configuration methods in a communication methodwhereby modulated signals of a plurality of channels are transmittedfrom a plurality of antennas at the same frequency, and an associatedtransmitting apparatus and receiving apparatus.

FIG. 19 is a block diagram showing an example of the transmit signalframe configuration transmitted by a base station according toEmbodiment 7 of the present invention. In FIG. 19, the vertical axisindicates frequency and the horizontal axis indicates time.

In this case, pilot symbols 1801 are inserted in a regular manner in achannel. A receiving apparatus separates a channel A signal and achannel B signal by means of these pilot symbols 1801, and can thendemodulate channel A information symbols 102 by estimating channel Afrequency offset and channel distortion.

At this time, pilot symbols are not inserted in a channel B. Performingcoding on channel A or making a channel A signal a pilot at this timemakes it possible for the receiving apparatus to demodulate channel Binformation symbols 102.

FIG. 20 is a block diagram showing an example of the configuration of atransmitting apparatus according to Embodiment 7 of the presentinvention. Parts in FIG. 20 identical to those in FIG. 3 are assignedthe same reference numerals as in FIG. 3, and detailed descriptionsthereof are omitted.

A coding section 1901 codes channel B transmit digital signal 211 on thebasis of channel A transmit digital signal 201, and outputs apost-coding transmit digital signal 1902 to serial/parallel conversionsection 212.

Then serial/parallel conversion section 212 converts post-codingtransmit digital signal 1902 to parallel data arranged in accordancewith frame configuration signal 222, and outputs post-conversionparallel signal 213 to inverse discrete Fourier transform section 204.Specifically, serial/parallel conversion section 212 configures a framewith the configuration shown in FIG. 19.

The configuration of a receiving apparatus will now be described. FIG.21 is a block diagram showing an example of the configuration of areceiving apparatus according to Embodiment 7 of the present invention.Parts in FIG. 21 identical to those in FIG. 4 are assigned the samereference numerals as in FIG. 4, and detailed descriptions thereof areomitted.

A demodulation section 2003 demodulates separated channel A parallelsignal 2001, and outputs a channel A received digital signal 2004.

A demodulation section 2005 demodulates separated channel B parallelsignal 2002 using channel A parallel signal 2001, and outputs a channelB received digital signal 2006.

The operations whereby a channel B signal is decoded and demodulatedbased on a channel A signal using the above transmitting apparatus andreceiving apparatus will now be described.

Explanations are given of the case in which channel A and channel B aredifferentially encoded.

FIG. 19 is one example of the frame configuration of the base stationtransmit signal according to this embodiment. In this case, pilotsymbols 1801 are inserted in a regular manner in a channel A signal. Inthis case, both estimation symbols 103 and pilot symbols 1801 are, forexample, known symbols (known pilots). However, their roles differ inthe receiver. Estimation symbols 103 are used to perform signalprocessing that separates multiplexed signals in channel A and channelB. On the other hand, channel B pilot symbols 1801 are signals to bereferences for demodulating channel A signals after separation, and aresymbols for, for example, estimating phase, amplitude, channeldistortion, and frequency offset in the I-Q plane.

Then, for example, with symbols of the same carrier and the same time ofchannel A and channel B, it is assumed that the symbol of channel B isdifferentially encoded in accordance with the symbol of channel A.

It is assumed that, in channel A, two bits transmitted by oneinformation symbol are shown as FIGS. 23A and 23B.

Then, for example, with symbols of the same carrier and the same time ofchannel A and channel B, it is assumed that the symbol of channel B isdifferentially encoded in accordance with the symbol of channel A.

FIGS. 22A through 22H are drawings showing examples of the signal pointarrangement in the I-Q plane when a channel B signal undergoesdifferential encoding with respect to a channel A signal. In FIGS. 22Athrough 22H, channel A and channel B signals are subjected to QPSK(Quadrature Phase Shift Keying) modulation.

The signal point when information ‘00’ is transmitted in channel Acarrier 1 time 4 is positioned as shown in FIG. 22A. At this time,differential encoding is performed for channel B carrier 1 time 4 withrespect to channel A carrier 1 time 4, and therefore when information‘00’, ‘01’, ‘11’, and ‘10’ is transmitted, the signal points arepositioned as shown in FIG. 22B. That is to say, the position of asymbol received in channel A is made the reference position when achannel B symbol is demodulated (in other words, the channel Binformation ‘00’ symbol position).

Similarly, the signal point when information ‘01’ is transmitted inchannel A carrier 1 time 4 is positioned as shown in FIG. 22C. At thistime, differential encoding is performed for channel B carrier 1 time 4with respect to channel A carrier 1 time 4, and therefore wheninformation ‘00’, ‘01’, ‘11’, and ‘10’ is transmitted, the signal pointsare positioned as shown in FIG. 22D.

Similarly, the signal point when information ‘11’ is transmitted inchannel A carrier 1 time 4 is positioned as shown in FIG. 22E. At thistime, differential encoding is performed for channel B carrier 1 time 4with respect to channel A carrier 1 time 4, and therefore wheninformation ‘00’, ‘01’, ‘11’, and ‘10’ is transmitted, the signal pointsare positioned as shown in FIG. 22F.

Similarly, the signal point when information ‘10 is transmitted inchannel A carrier 1 time 4 is positioned as shown in FIG. 22G. At thistime, differential encoding is performed for channel B carrier 1 time 4with respect to channel A carrier 1 time 4, and therefore wheninformation ‘00’, ‘01’, ‘11’, and ‘10’ is transmitted, the signal pointsare positioned as shown in FIG. 22H.

Next, an example of the differential coding operation with BPSKmodulation will be described. FIGS. 23A through 23D are drawings showingexamples of the signal point arrangement in the I-Q plane when a channelB signal undergoes differential encoding with respect to a channel Asignal. In FIGS. 23A through 23D, channel A and channel B signals aresubjected to BPSK modulation.

The signal point when information ‘1’ is transmitted in channel Acarrier 1 time 4 is positioned at 2201 as shown in FIG. 23A. At thistime, differential encoding is performed for channel B carrier 1 time 4with respect to channel A carrier 1 time 4, and therefore wheninformation ‘0’ is transmitted, the signal point is positioned at 2202as shown in FIG. 23B, and when information ‘1’ is transmitted, thesignal point is positioned at 2203. That is to say, the position of asymbol received in channel A is made the reference position when achannel B symbol is demodulated (in other words, the channel Binformation ‘1’ symbol position).

In contrast to this, the signal point when information ‘0’ istransmitted in channel A carrier 1 time 4 is positioned at 2204 as shownin FIG. 23C. At this time, differential encoding is performed forchannel B carrier 1 time 4 with respect to channel A carrier 1 time 4,and therefore when information ‘0’ is transmitted, the signal point ispositioned at 2206 as shown in FIG. 23D, and when information ‘1’ istransmitted, the signal point is positioned at 2205.

An example will now be described in which a channel A signalconstituting the coding reference is a BPSK signal, and a channel Bsignal coded based on channel A is a QPSK signal. FIGS. 24A through 24Dare drawings showing examples in which channel B M-ary modulation (here,QPSK modulation) I-Q plane signal point arrangement is performed basedon channel A PSK modulation (here, BPSK (Binary Phase Shift Keying)modulation). The channel A and channel B modulation methods are assumedto be different at this time. Another feature is that the channel Amodulation method is PSK modulation.

The signal point when information ‘0’ is transmitted in channel Acarrier 1 time 4 is positioned as shown in FIG. 24A. At this time, forchannel B carrier 1 time 4, the signal point arrangement for information‘00’, ‘01’, ‘11’, and ‘10’ is determined with respect to the channel Acarrier 1 time 4 signal point position. The signal point arrangement atthis time is as shown in FIG. 24B. That is to say, a point whose phaseis advanced by 45 degrees from the position of a symbol received inchannel A is made the reference position when a channel B symbol isdemodulated (in other words, the channel B information ‘00’ symbolposition).

Similarly, the signal point when information ‘1’ is transmitted inchannel A carrier 1 time 4 is positioned as shown in FIG. 24C. At thistime, for channel B carrier 1 time 4, the signal point arrangement forinformation ‘00’, ‘01’, ‘11’, and ‘10’ is determined with respect to thechannel A carrier 1 time 4 signal point position. The signal pointarrangement at this time is as shown in FIG. 24D.

An example will now be described in which a channel A signalconstituting the coding reference is a BPSK signal, and a channel Bsignal coded based on channel A is a 16QAM signal. FIGS. 25A through 25Dare drawings showing examples in which channel B M-ary modulation (here,16QAM (16 Quadrature Amplitude Modulation)) I-Q plane signal pointarrangement is performed based on channel A PSK modulation (here, BPSKmodulation). In FIGS. 25A through 25D, the channel A and channel Bmodulation methods are assumed to be different. Another feature is thatthe channel A modulation method is PSK modulation.

The signal point when information ‘0’ is transmitted in channel Acarrier 1 time 4 is positioned as shown in FIG. 25A. At this time, forchannel B carrier 1 time 4, the signal point arrangement for 4-bitinformation ‘0000’, . . . , ‘1111’ is determined based on the positionof the signal point received at channel A carrier 1 time 4. The signalpoint arrangement at this time is as shown in FIG. 25B.

Similarly, the signal point when information ‘1’ is transmitted inchannel A carrier 1 time 4 is positioned as shown in FIG. 25C. At thistime, for channel B carrier 1 time 4, the signal point arrangement for4-bit information ‘0000’, . . . , ‘1111’ is determined based on theposition of the signal point received at channel A carrier 1 time 4. Thesignal point arrangement at this time is as shown in FIG. 25D.

FIGS. 26A through 26D are drawings showing examples in which channel BM-ary modulation (here, 16QAM) I-Q plane signal point arrangement isperformed based on channel A PSK modulation (here, QPSK modulation). Thechannel A and channel B modulation methods are assumed to be differentat this time. Another feature is that the channel A modulation method isPSK modulation.

When information ‘00’ is transmitted in channel A carrier 1 time 4, forchannel B carrier 1 time 4 the signal point arrangement for 4-bitinformation ‘0000’, . . . , ‘1111’ is determined with respect to channelA carrier 1 time 4 signal point position 2501. The signal pointarrangement at this time is as shown in FIG. 26A.

When information ‘01’ is transmitted in channel A carrier 1 time 4, forchannel B carrier 1 time 4 the signal point arrangement for 4-bitinformation ‘0000’, . . . , ‘1111’ is determined with respect to channelA carrier 1 time 4 signal point position 2502. The signal pointarrangement at this time is as shown in FIG. 26B.

When information ‘11’ is transmitted in channel A carrier 1 time 4, forchannel B carrier 1 time 4 the signal point arrangement for 4-bitinformation ‘0000’, . . . , ‘1111’ is determined with respect to channelA carrier 1 time 4 signal point position 2503. The signal pointarrangement at this time is as shown in FIG. 26C.

When information ‘10’ is transmitted in channel A carrier 1 time 4, forchannel B carrier 1 time 4 the signal point arrangement for 4-bitinformation ‘0000’, . . . , ‘1111’ is determined with respect to channelA carrier 1 time 4 signal point position 2504. The signal pointarrangement at this time is as shown in FIG. 26D.

FIG. 27 is a drawing showing an example of base station transmit signalframe configurations of this embodiment.

In FIG. 27, pilot symbols 1801 are inserted in a regular fashion in bothchannel A and channel B.

At this time, estimation symbols 103 are symbols used by the receiver toseparate channel A and channel B, and channel A pilot symbols 1801 aresymbols for estimating channel A signal channel distortion, frequencyoffset, and such like distortion components in the channel Ademodulation section after channel A and channel B signal separation inthe receiver.

Similarly, channel B pilot symbols 1801 are symbols for estimatingchannel B signal channel distortion, frequency offset, and such likedistortion components in the channel B demodulation section afterchannel A and channel B signal separation in the receiver.

In FIG. 27, estimation symbols 103 for when channel A and channel Bsignal separation is performed are not multiplexed in channel A andchannel B. Another feature is that aforementioned pilot symbols 1801 aremultiplexed.

In the case in FIG. 27, both estimation symbols 103 and pilot symbols1801 are, for example, known symbols (known pilots). However, theirroles differ in the receiver. Estimation symbols 103 are used to performsignal processing that separates channel A and channel B multiplexedsignals.

Then, when channel A information symbols are demodulated, channel Apilot symbols 1801 and channel B pilot symbols 1801 are used to estimatechannel distortion, frequency offset, and phase and amplitude in the I-Qplane.

Similarly, when channel B information symbols are demodulated, channel Apilot symbols 1801 and channel B pilot symbols 1801 are used to estimatechannel distortion, frequency offset, and phase and amplitude in the I-Qplane.

Then a modulated signal is generated according to FIG. 27 frameconfiguration information contained in frame configuration signal 222output from frame configuration signal generation section 221 in FIG. 3.

Next, the arrangement of pilot symbols according to this embodiment willbe described. FIG. 28 is a drawing showing an example of pilot symbolsignal point arrangement in the I-Q plane according to this embodiment.

In FIG. 28, reference numeral 2701 indicates a known pilot symbol, anddenotes signal point positioning at a specific location. Referencenumeral 2702 indicates known BPSK pilot symbols, which are BPSKmodulated and positioned in a regular fashion.

FIG. 29 is a drawing showing an example of base station transmit signalframe configurations according to this embodiment. In FIG. 29, thevertical axis indicates frequency and the horizontal axis indicatestime. A feature in FIG. 29 is that pilot symbols are not inserted forestimating channel distortion, frequency offset, and such likedistortion after channel A and B separation. Another feature is that thechannel A modulation method is PSK modulation.

At this time, channel A undergoes differential encoding on the frequencyaxis or time axis. Then in channel B, information bits are assigned forchannel A signal point arrangement.

A description will now be given of the method of performing differentialencoding of channel A and channel B, and the method of performingchannel B signal point arrangement based on a channel A signal point,with the frame configurations in FIG. 29.

In FIG. 29, channel A is PSK modulated, and is subjected to differentialencoding with, for example, an adjacent symbol on the frequency axis ortime axis. Consequently, it is not necessary to insert pilot symbols.Then channel A and channel B undergo differential encoding as in FIG. 22or FIG. 23, for example. Alternatively, channel B signal points arearranged on the basis of a channel A signal point as in FIG. 24, FIG.25, or FIG. 26.

By coding in this way, in the receiver it is possible to estimatechannel distortion, frequency offset, and phase in the I-Q plane—thatis, to make pilot symbols—by means of a channel A signal when a channelB signal is demodulated.

FIG. 20 and FIG. 21 show examples of the configurations of atransmitting apparatus and receiving apparatus in this case. At thistime, points of difference in operation when transmitting or receiving aFIG. 19 frame are that, in FIG. 20, channel A transmit digital signal201 undergoes differential encoding, and in channel A demodulationsection 2003 in FIG. 21, differential detection (differentially coherentdetection) is performed, and channel A received digital signal 2004 isoutput.

FIG. 30 is a drawing showing an example of the configuration of areceiving apparatus according to this embodiment. Parts in FIG. 30identical to those in FIG. 4 are assigned the same reference numerals asin FIG. 4, and detailed descriptions thereof are omitted.

A demodulation section 2903 demodulates a separated channel A parallelsignal 2901, and outputs a received digital signal 2904.

A demodulation section 2905 demodulates a separated channel B parallelsignal 2902, and outputs a received digital signal 2906.

FIG. 31 is a block diagram showing an example of a demodulation sectionof this embodiment. Specifically, FIG. 31 shows the configuration of thechannel B demodulation section as an example of the configuration ofchannel A and channel B demodulation sections according to thisembodiment.

A channel distortion estimation section 3002 estimates channeldistortion from a channel B parallel signal 3001, and outputs a channeldistortion estimation signal 3003 to an information symbol demodulationsection 3006.

A frequency offset estimation section 3004 estimates frequency offsetfrom channel B parallel signal 3001, and outputs a frequency offsetestimation signal 3005 to information symbol demodulation section 3006.

Using channel distortion estimation signal 3003 and frequency offsetestimation signal 3005, information symbol demodulation section 3006demodulates channel B parallel signal 3001 and outputs a receiveddigital signal 3007.

FIG. 32 is a block diagram showing an example of a demodulation sectionof this embodiment. Specifically, FIG. 32 shows the configuration of thechannel B demodulation section as an example of the configuration ofchannel A and channel B demodulation sections according to thisembodiment.

A channel distortion estimation section 3102 estimates channeldistortion from a channel A parallel signal 3108, and outputs a channeldistortion estimation signal 3103 to an information symbol demodulationsection 3106.

A frequency offset estimation section 3104 estimates frequency offsetfrom channel A parallel signal 3108, and outputs a frequency offsetestimation signal 3105 to information symbol demodulation section 3106.

Using channel distortion estimation signal 3103 and frequency offsetestimation signal 3105, information symbol demodulation section 3106demodulates channel B parallel signal 3101 and outputs a channel Breceived digital signal 3107.

FIG. 33 is a block diagram showing an example of a demodulation sectionof this embodiment. Specifically, FIG. 33 shows the configuration of thechannel B demodulation section as an example of the configuration ofchannel A and channel B demodulation sections according to thisembodiment.

A channel distortion estimation section 3202 estimates channeldistortion from a channel B parallel signal 3201 and channel A parallelsignal 3208, and outputs a channel distortion estimation signal 3203 toan information symbol demodulation section 3206.

A frequency offset estimation section 3204 estimates frequency offsetfrom channel B parallel signal 3201 and channel A parallel signal 3208,and outputs a frequency offset estimation signal 3205 to informationsymbol demodulation section 3206.

Using channel distortion estimation signal 3203 and frequency offsetestimation signal 3205, information symbol demodulation section 3206demodulates channel B parallel signal 3201 and outputs a channel Breceived digital signal 3207.

FIG. 34 is a block diagram showing an example of a demodulation sectionof this embodiment. Specifically, FIG. 34 shows the configuration of thechannel B demodulation section as an example of the configuration ofchannel A and channel B demodulation sections according to thisembodiment.

Using a channel A parallel signal 3302, an information symboldemodulation section 3303 demodulates a channel B parallel signal 3301and outputs a channel B received digital signal 3304.

FIG. 35 is a block diagram showing an example of the configuration of areceiving apparatus according to this embodiment. Parts in FIG. 35identical to those in FIG. 4 or FIG. 30 are assigned the same referencenumerals as in FIG. 4 or FIG. 30, and detailed descriptions thereof areomitted.

Features of FIG. 35 are that separated channel A parallel signal 2901and separated channel B parallel signal 2902 are input to channel Ademodulation section 2903, and that channel A demodulation is performedby means of separated channel A parallel signal 2901 and separatedchannel B parallel signal 2902.

Similarly, features are that separated channel A parallel signal 2901and separated channel B parallel signal 2902 are input to channel Bdemodulation section 2905, and that channel B demodulation is performedby means of separated channel A parallel signal 2901 and separatedchannel B parallel signal 2902.

In FIG. 35, the example of the channel A and channel B demodulationsections is as shown in FIG. 33. That is to say, demodulation section2903 and demodulation section 2905 have the configuration of thedemodulation section in FIG. 33. Here, channel A demodulation section2903 will be described as an example.

Channel distortion estimation section 3202 extracts pilot symbolsinserted in channel A and channel B from channel A parallel signal 3201corresponding to separated channel A parallel signal 2901 in FIG. 35,and channel B parallel signal 3208 (FIG. 27) corresponding to separatedchannel B parallel signal 2902 in FIG. 35, estimates channel distortion,and outputs channel distortion estimation signal 3203 to informationsymbol demodulation section 3206.

Similarly, frequency offset estimation section 3204 extracts pilotsymbols inserted in channel A and channel B from channel A parallelsignal 3201 corresponding to separated channel A parallel signal 2901 inFIG. 35, and channel B parallel signal 3208 (FIG. 27) corresponding toseparated channel B parallel signal 2902 in FIG. 35, estimates frequencyoffset, and outputs frequency offset estimation signal 3205 toinformation symbol demodulation section 3206.

Then, using channel distortion estimation signal 3203 and frequencyoffset estimation signal 3205, information symbol demodulation section3206 eliminates frequency offset, channel distortion, and suchlikedistortion from channel A parallel signal 3201, performs demodulation,and outputs channel A received digital signal 3007.

By estimating channel distortion and frequency offset by using channel Aand channel B pilot symbols in this way, estimation precision isimproved, and reception sensitivity characteristics are improved.

The above description refers to the configuration in FIG. 33 in which achannel distortion estimation section and frequency offset estimationsection are provided, but the present invention can be similarlyimplemented with a configuration in which only one or the other isprovided.

FIG. 36 is a block diagram showing an example of a demodulation sectionof this embodiment. Specifically, FIG. 36 shows the configuration of thechannel B demodulation section as an example of the configuration ofchannel A and channel B demodulation sections according to thisembodiment. Parts in FIG. 36 identical to those in FIG. 33 are assignedthe same reference numerals as in FIG. 33, and detailed descriptionsthereof are omitted.

A demodulation section of a receiving apparatus of this embodiment willnow be described. FIG. 31 is a block diagram showing the configurationof a receiving apparatus of this embodiment. Specifically, FIG. 31 is ablock diagram showing the detailed configuration of demodulation section2003 in FIG. 21.

In FIG. 31, channel distortion estimation section 3002 extracts pilotsymbols—for example, pilot symbols 1801 inserted in channel A in FIG.19—from channel A parallel signal 3001 corresponding to separatedchannel A parallel signal 2001 in FIG. 21, and estimates channeldistortion.

Similarly, frequency offset estimation section 3004 extracts pilotsymbols—for example, pilot symbols 1801 inserted in channel A in FIG.19—from channel A parallel signal 3001, and estimates frequency offset.

Then, using channel distortion estimation signal 3003 and frequencyoffset estimation signal 3005, information symbol demodulation section3006 eliminates frequency offset, channel distortion, and suchlikedistortion from channel A parallel signal 3001, and performsdemodulation.

Channel B demodulation section 2005 has separated channel A parallelsignal 2001 and separated channel B parallel signal 2002 as input,demodulates channel B information symbols 102 in FIG. 19, and outputschannel B received digital signal 2006. Drawings showing the detailedconfiguration of channel B demodulation section 2005 at this time areFIG. 34 and FIG. 36.

In FIG. 34, information symbol demodulation section 3303 has as inputchannel A parallel signal 3302 corresponding to separated channel Aparallel signal 2001 in FIG. 21, and channel B parallel signal 3301corresponding to separated divided channel B parallel signal 2002 inFIG. 21, and performs differential detection (differentially coherentdetection).

In FIG. 36, channel distortion estimation section 3202 extracts pilotsymbols—for example, channel A pilot symbols 1801 in FIG. 19—fromchannel A parallel signal 3208 corresponding to separated channel Aparallel signal 2001 in FIG. 21, and estimates channel distortion.

Similarly, frequency offset estimation section 3204 extracts pilotsymbols—for example, channel A pilot symbols 1801 in FIG. 19—fromchannel A parallel signal 3208 corresponding to separated channel Aparallel signal 2001 in FIG. 21, and estimates frequency offset.

Then, using channel distortion estimation signal 3203 and frequencyoffset estimation signal 3205, information symbol demodulation section3206 eliminates frequency offset, channel distortion, and suchlikedistortion from channel A parallel signal 3208 and channel B parallelsignal 3201, performs differential detection (differentially coherentdetection) on the channel B parallel signal and channel A parallelsignal, and outputs a channel B received digital signal 3207.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, a channel B signal undergoes differential encoding bymeans of a channel A signal, and pilot symbols are not inserted inchannel B, with the result that transmission speed is improved comparedwith a system in which pilot symbols are inserted in channel B.

The method of differential encoding for channel A and channel B is notlimited to this. For example, differential encoding may be performedonly for certain specific symbols. Also, it is not necessary for channelA and channel B differentially coded symbols to be symbols of the samecarrier or the same time. Furthermore, a description has been givenusing BPSK and QPSK as examples of differential encoding, but this isnot a limitation, and in the case of PSK modulation, in particular, thepresent invention is easy to implement. The channel used as a referencewhen performing differential encoding must transmit constantly, and thischannel is suitable for the transmission of control information, such ascommunication conditions and channel configuration information, forexample.

The above description refers to configurations in FIG. 32 and FIG. 36 inwhich a channel distortion estimation section and frequency offsetestimation section are provided, but the present invention can besimilarly implemented with a configuration in which only one or theother is provided.

A transmitting apparatus and receiving apparatus are not limited to theconfigurations in FIG. 20 and FIG. 21. Also, the use of multiplex framesand non-multiplexed frames with two channels and two antennas has beendescribed as an example, but the present invention is not limited tothis. For example, it is possible to implement the present inventionsimilarly with multiplex frames using three channels and three antennas,and multiplex frames using two channels and two of three antennas. Inthis case, when using 3-channel multiplexing, if the additional channelis designated channel C, channel C is differentially coded with channelA. Also, the frame configurations are not limited to those in FIG. 19.Furthermore, an example has been described in which OFDM is used as thecommunication method, but it is possible to implement the presentinvention similarly with a multicarrier method, a spread spectrumcommunication method, or a single-carrier method. Moreover, a spreadspectrum communication method may be used as the method for each carrierin a multicarrier system. Thus, it is possible to implement the presentinvention similarly with OFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Next, a case will be described in which channel B is coded based on achannel A signal.

FIG. 19 is an example of the base station transmit signal frameconfiguration according to this embodiment. In this case, pilot symbols1801 are inserted in a channel A. At this time, both estimation symbols103 and pilot symbols 1801 are, for example, known symbols (knownpilots). However, their roles differ in the receiver. Estimation symbols103 are used to perform signal processing that separates multiplexedsignals in channel A and channel B.

Estimation symbols 103 are used to perform signal processing thatseparates multiplexed signals in channel A and channel B. On the otherhand, channel B pilot symbols 1801 are signals to be references fordemodulating channel A signals after separation, and are symbols for,for example, estimating phase, amplitude, channel distortion, andfrequency offset in the I-Q plane.

Next, the relationship between the channel A and the channel B isexplained.

For example, FIG. 24 shows one example of the relationship when channelA undergoes the BPSK modulation and channel B undergoes the QPSKmodulation.

It is assumed that, in the channel A, one bit to be transmitted by oneinformation symbol is shown as FIGS. 24A and 24B.

Then, the channel B is encoded in accordance with the channel A signal.For example, explanations are given of the relationship between thechannel A carrier 1 time 4 and the channel B carrier 1 time 4 in theframe configuration in FIG. 24.

The signal point when information ‘0’ is transmitted in channel Acarrier 1 time 4 is positioned as shown in FIG. 24A. At this time,differential encoding is performed for channel B carrier 1 time 4 withrespect to channel A carrier 1 time 4, and therefore when information‘00’, ‘01’, ‘11’, and ‘10’ is transmitted, the signal points arepositioned as shown in FIG. 24B.

Similarly, the signal point when information ‘1’ is transmitted inchannel A carrier 1 time 4 is positioned as shown in FIG. 24C. At thistime, differential encoding is performed for channel B carrier 1 time 4with respect to channel A carrier 1 time 4, and therefore wheninformation ‘00’, ‘01’, ‘11’, and ‘10’ is transmitted, the signal pointsare positioned as shown in FIG. 24D.

In this way, channel B is encoded in accordance with the signal point ofchannel A. Then, for example, with symbols of the same carrier and thesame time of channel A and channel B, it is assumed that the symbol ofchannel B is encoded in accordance with the symbol of channel A.

As shown in FIG. 24, when channel B is encoded in accordance withchannel A, channel A can be used as a pilot symbol for channel B. Thatis to say, when the channel B signal in the receiver is demodulated, itis possible to estimate frequency offset, channel distortion, and phasein the I-Q plane by using the channel A signal. Therefore, the channel Asignal can be used as a pilot symbol for channel B signal.

Then, FIG. 25 shows one example of the relationship when channel Aundergoes BPSK modulation and channel B undergoes 16 QAM.

One bit to be transmitted by one information symbol in the channel A isrepresented by FIGS. 25A and 24C.

Then, the channel B is encoded in accordance with the channel A signal.For example, explanations are given of the relationship between thechannel A carrier 1 time 4 and the channel B carrier 1 time 4 in theframe configuration in FIG. 19.

The signal point when information ‘0’ is transmitted in channel Acarrier 1 time 4 is positioned as shown in FIG. 25A. At this time,encoding is performed for channel B carrier 1 time 4 with respect tochannel A carrier 1 time 4, and therefore, four bits of information arepositioned as shown in FIG. 25B.

Similarly, the signal point when information ‘1’ is transmitted inchannel A carrier 1 time 4 is positioned as shown in FIG. 25C. At thistime, encoding is performed for channel B carrier 1 time 4 with respectto channel A carrier 1 time 4, and therefore four bits of informationare positioned as shown in FIG. 25D.

In this way, channel B is encoded in accordance with the signal point ofchannel A. Then, for example, with symbols of the same carrier and thesame time of channel A and channel B, it is assumed that the symbol ofchannel B is encoded in accordance with the symbol of channel A.

As shown in FIG. 25, when channel B is encoded in accordance withchannel A, channel A can be used as a pilot symbol for channel B. Thatis to say, when the channel B signal in the receiver is demodulated, itis possible to estimate frequency offset, channel distortion, and phasein the I-Q plane by using the channel A signal. Therefore, the channel Asignal can be used as a pilot symbol for channel B signal.

Then, FIG. 26 shows one example of the relationship when channel Aundergoes QPSK modulation and channel B undergoes 16 QAM.

In channel A, two bits transmitted by one information symbol are shownas 2501 in FIG. 26.

Then, the channel B is encoded in accordance with the channel A signal.For example, explanations are given of the relationship between thechannel A carrier 1 time 4 and the channel B carrier 1 time 4 in theframe configuration in FIG. 19.

The signal point when information ‘00’ is transmitted in channel Acarrier 1 time 4 is positioned at 2501 in FIG. 26A. At this time,encoding is performed for channel B carrier 1 time 4 with respect tochannel A carrier 1 time 4, and therefore four bits of information arepositioned as shown in FIG. 26A.

Similarly, the signal point when information ‘01’ is transmitted inchannel A carrier 1 time 4 is positioned at 2501 as shown in FIG. 26B.At this time, encoding is performed for channel B carrier 1 time 4 withrespect to channel A carrier 1 time 4, and therefore four bits ofinformation are arranged as shown in FIG. 26B.

Similarly, the signal point when information ‘11’ is transmitted inchannel A carrier 1 time 4 is positioned at 2501 as shown in FIG. 26C.At this time, encoding is performed for channel B carrier 1 time 4 withrespect to channel A carrier 1 time 4, and therefore four bits ofinformation are arranged as shown in FIG. 26C.

Similarly, the signal point when information ‘10’ is transmitted inchannel A carrier 1 time 4 is positioned at 2501 as shown in FIG. 26D.At this time, encoding is performed for channel B carrier 1 time 4 withrespect to channel A carrier 1 time 4, and therefore four bits ofinformation are arranged as shown in FIG. 26D.

In this way, channel B is encoded in accordance with the signal point ofchannel A. Then, for example, with symbols of the same carrier and thesame time of channel A and channel B, it is assumed that the symbol ofchannel B is encoded in accordance with the symbol of channel A

As shown in FIG. 26, when channel B is encoded in accordance withchannel A, channel A can be used as a pilot symbol for channel B. Thatis to say, when the channel B signal in the receiver is demodulated, itis possible to estimate frequency offset, channel distortion, and phasein the I-Q plane by using the channel A signal. Therefore, the channel Asignal can be used as a pilot symbol for channel B signal.

Next, the transmitting apparatus is explained.

FIG. 20 is one example of the configuration of the transmittingapparatus that performs encoding as in FIG. 24, FIG. 25, or FIG. 26 inthe frame configuration in FIG. 19.

Referring to FIG. 20, explanations are given of parts that are differentfrom the operation of FIG. 3, namely, channel B.

In channel B, encoding is performed. A coding section 1901 receiveschannel A transmit digital signal 201 and channel B transmit digitalsignal 211 as input, performs coding, like FIG. 24, FIG. 25, and FIG.26, and outputs a post-coding transmit digital signal 1902.

Next, the configuration of the receiving apparatus is explained.

FIG. 21 is one example of the configuration of the receiving apparatusthat receives the decoded transmit signal as in FIG. 24, FIG. 25, orFIG. 26 in the frame configuration in FIG. 19.

Referring to FIG. 21, explanations are given of parts that are differentfrom the operation of FIG. 4.

Channel A demodulation section 2003 receives separated channel Aparallel signal 2001 as input, demodulates channel A information symbol102 in FIG. 19, and outputs channel A received digital signal 2004. FIG.31 shows the detailed configuration of channel A demodulation section2003 at this time.

In FIG. 31, channel distortion estimation section 3002 receives channelA parallel signal 3001 corresponding to separated channel A parallelsignal 2001 in FIG. 21 as input, extracts, for example, pilot symbols1801 inserted in channel A in FIG. 19, estimates channel distortion, andoutputs channel distortion estimation signal 3003.

Similarly, frequency offset estimation section 3004 receives channel Aparallel signal 3001 as input, extracts, for example, pilot symbols 1801inserted in channel A in FIG. 19, estimates frequency offset, andoutputs frequency offset estimation signal 3005.

Then, information symbol demodulation section 3006 receives channel Aparallel signal 3001, channel distortion estimation signal 3003, andfrequency offset estimation signal 3005 as input, eliminates frequencyoffset, channel distortion, and suchlike distortion from, performsdemodulation, and outputs channel A received digital signal 3007.

Channel B demodulation section 2005 receives separated channel Aparallel signal 2001 and separated channel B parallel signal 2002 asinput, demodulates channel B information symbols 102 in FIG. 19, andoutputs channel B received digital signal 2006. A drawing showing thedetailed configuration of channel B demodulation section 2005 at thistime is FIG. 36.

The coding method of channel A and channel B is not limited to this. Forexample, coding may be performed only for certain specific symbols.Also, it is not necessary for channel A and channel B coded symbols tobe symbols of the same carrier or the same time. Furthermore, adescription has been given using BPSK and QPSK as examples ofdifferential encoding, but this is not a limitation, and in the case ofPSK modulation, in particular, the present invention is easy toimplement. The channel used as a reference when coding must transmitconstantly, and this channel is suitable for the transmission of controlinformation, such as communication conditions and channel configurationinformation, for example.

The above description refers to a configuration in FIG. 36 in which achannel distortion estimation section and frequency offset estimationsection are provided, but the present invention can be similarlyimplemented with a configuration in which only one or the other isprovided.

A transmitting apparatus and receiving apparatus are not limited to theconfigurations in FIG. 20 and FIG. 21. Also, the use of multiplex framesand non-multiplexed frames with two channels and two antennas has beendescribed as an example, but the present invention is not limited tothis. For example, it is possible to implement the present inventionsimilarly with multiplex frames using three channels and three antennas,and multiplex frames using two channels and two of three antennas. Inthis case, when using 3-channel multiplexing, if the additional channelis designated channel C, channel C is coded with channel A. Also, theframe configurations are not limited to those in FIG. 19. Furthermore,an example has been described in which OFDM is used as the communicationmethod, but it is possible to implement the present invention similarlywith a multicarrier method, a spread spectrum communication method, or asingle-carrier method. Moreover, a spread spectrum communication methodmay be used as the method for each carrier in a multicarrier system.Thus, it is possible to implement the present invention similarly withOFDM-CDM (Orthogonal Frequency Division Multiplexing-Code DivisionMultiplexing).

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Thus, a channel B signal is encoded by a channel A signal and pilotsymbols are not inserted in channel B, so that transmission speed isimproved compared with a system in which pilot symbols are inserted inchannel B.

In the above description, the coding method of channel A and channel Bis not limited to this, and, for example, coding may be performed onlyfor certain specific symbols. Also, it is not necessary for channel Aand channel B coded symbols to be symbols of the same carrier or thesame time. Furthermore, a description has been given using BPSK and QPSKas examples of differential encoding, but this is not a limitation, andin the case of PSK modulation, in particular, the present invention iseasy to implement. The channel used as a reference when coding musttransmit constantly, and this channel is suitable for the transmissionof control information, such as communication conditions and channelconfiguration information, for example.

A transmitting apparatus and receiving apparatus are not limited to theconfigurations in FIG. 20 and FIG. 21. Also, the use of multiplex framesand non-multiplexed frames with two channels and two antennas has beendescribed as an example, but the present invention is not limited tothis. For example, it is possible to implement the present inventionsimilarly with multiplex frames using three channels and three antennas,and multiplex frames using two channels and two of three antennas. Inthis case, when using 3-channel multiplexing, if the additional channelis designated channel C, channel C is coded with channel A. Also, theframe configurations are not limited to those in FIG. 29. Furthermore,an example has been described in which OFDM is used as the communicationmethod, but it is possible to implement the present invention similarlywith a multicarrier method, a spread spectrum communication method, or asingle-carrier method. Moreover, a spread spectrum communication methodmay be used as the method for each carrier in a multicarrier system.Thus, it is possible to implement the present invention similarly withOFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

As described above, channel A is differentially coded on the frequencyaxis or time axis, a channel A and channel B signal is coded by means ofa channel A signal, and pilot symbols are not inserted in channel A orchannel B, with the result that transmission speed is improved comparedwith a system in which pilot symbols are inserted in channel A andchannel B.

The method of inserting pilot symbols in channel A and channel B willnow be described using FIG. 3, FIG. 27, FIG. 30, FIG. 33, and FIG. 35.

FIG. 27 is an example of the base station transmit signal frameconfiguration according to this embodiment. In this case, pilot symbols1801 are inserted in both channel A and channel B. In the case, bothestimation symbols 103 and pilot symbols 1801 are, for example, knownreference symbols (known pilots). However, their roles differ in thereceiver. Estimation symbols 103 are used to perform signal processingthat separates channel A and channel B multiplexed signals.

Then, when channel A information symbols are demodulated, channel Apilot symbols 1801 and channel B pilot symbols 1801 are used to estimatechannel distortion, frequency offset, and phase and amplitude in the I-Qplane.

Similarly, when channel B information symbols are demodulated, channel Apilot symbols 1801 and channel B pilot symbols 1801 are used to estimatechannel distortion, frequency offset, and phase and amplitude in the I-Qplane.

Next, the transmitting apparatus is explained.

FIG. 3 shows one example of the configuration of the transmittingapparatus that transmits the signal of the frame configuration in FIG.27.

Next, the configuration of the receiving apparatus is explained.

FIG. 35 is an example of the configuration of a receiving apparatus thatreceives the signal of the frame configuration in FIG. 27.

In FIG. 35, the example of the channel A and channel B demodulationsections is as shown in FIG. 33.

Here, channel A demodulation section 2903 will be described as anexample.

Channel distortion estimation section 3202 receives channel A parallelsignal 3201 corresponding to separated channel A parallel signal 2901 inFIG. 35 and channel B parallel signal 3208 corresponding to separatedchannel B parallel signal 2902 in FIG. 35 as input, extracts pilotsymbols 1801 inserted in channel A and pilot symbols 1801 inserted inchannel B in FIG. 27, estimates channel distortion, and outputs channeldistortion estimation signal 3203.

Similarly, frequency offset estimation section 3204 receives channel Aparallel signal 3201 corresponding to separated channel A parallelsignal 2901 in FIG. 35 and channel B parallel signal 3208 correspondingto separated channel B parallel signal 2902 in FIG. 35 as input,extracts pilot symbols 1801 inserted in channel A and pilot symbols 1801inserted in channel B in FIG. 27, estimates frequency offset, andoutputs frequency offset estimation signal 3206.

Then, information symbol demodulation section 3206 receives channel Aparallel signal 3201, channel distortion estimation signal 3203, andfrequency offset estimation signal 3206 as input, eliminates frequencyoffset, channel distortion, and suchlike distortion, performsdemodulation, and outputs channel A received digital signal 3007.

Channel distortion estimation section 3202 receives channel B parallelsignal 3201 corresponding to separated channel B parallel signal 2902 inFIG. 35 and channel A parallel signal 3208 corresponding to separatedchannel A parallel signal 2901 in FIG. 35 as input, extracts pilotsymbols 1801 inserted in channel A and pilot symbols 1801 inserted inchannel B in FIG. 27, estimates channel distortion, and outputs channeldistortion estimation signal 3203.

Similarly, frequency offset estimation section 3204 receives channel Bparallel signal 3201 corresponding to separated channel B parallelsignal 2902 in FIG. 35 and channel A parallel signal 3208 correspondingto separated channel A parallel signal 2901 in FIG. 35 as input,extracts pilot symbols 1801 inserted in channel A and pilot symbols 1801inserted in channel B in FIG. 27, estimates frequency offset, andoutputs frequency offset estimation signal 3206.

Then, information symbol demodulation section 3206 receives channel Bparallel signal 3201, channel distortion estimation signal 3203, andfrequency offset estimation signal 3206 as input, eliminates frequencyoffset, channel distortion, and suchlike distortion, performsdemodulation, and outputs channel B received digital signal 3007.

By estimating channel distortion and frequency offset using channel Aand channel B pilot symbols in this way, estimation precision isimproved, and reception sensitivity characteristics are improved.

The above description refers to the configuration in FIG. 33 in which achannel distortion estimation section and frequency offset estimationsection are provided, but the present invention can be similarlyimplemented with a configuration in which only one or the other isprovided.

A transmitting apparatus and receiving apparatus are not limited to theconfigurations in FIG. 3 and FIG. 35. Also, the use of multiplex framesand non-multiplexed frames with two channels and two antennas has beendescribed as an example, but the present invention is not limited tothis. For example, it is possible to implement the present inventionsimilarly with multiplex frames using three channels and three antennas,and multiplex frames using two channels and two of three antennas. Inthis case, when using 3-channel multiplexing, estimating channeldistortion and frequency offset using pilot symbols of three channelsenables estimation precision to be improved. Also, the frameconfigurations are not limited to those in FIG. 27. Furthermore, anexample has been described in which OFDM is used as the communicationmethod, but it is possible to implement the present invention similarlywith a multicarrier method, a spread spectrum communication method, or asingle-carrier method. Moreover, a spread spectrum communication methodmay be used as the method for each carrier in a multicarrier system.Thus, it is possible to implement the present invention similarly withOFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, estimation precision is improved by estimatingfrequency offset and channel distortion using channel A and channel Bpilots, as a result of which channel A and channel B demodulatereception sensitivity are improved.

Embodiment 8

In Embodiment 8 of the present invention, a description is given of atransmitting apparatus provided with one transmission baseband frequencysource and one radio section frequency source, and a receiving apparatusprovided with one reception baseband frequency source and one radiosection frequency source, in a transmission method whereby modulatedsignals of a plurality of channels are transmitted from a plurality ofantennas in the same frequency band.

FIG. 37 is a block diagram showing an example of the configuration of atransmitting apparatus according to Embodiment 8 of the presentinvention. Parts in FIG. 37 identical to those in FIG. 3 are assignedthe same reference numerals as in FIG. 3, and detailed descriptionsthereof are omitted.

A frequency source 3601 generates a transmission baseband signaloperating frequency signal 3602, and outputs operating frequency signal3602 to serial/parallel conversion section 202, inverse discrete Fouriertransform section 204, serial/parallel conversion section 212, inversediscrete Fourier transform section 214, and frame configuration signalgeneration section 221.

A frequency source 3603 generates a radio section operating frequencysignal 3604, and outputs operating frequency signal 3604 to radiosection 206 and radio section 216.

The operation of the transmitting apparatus in FIG. 37 will now bedescribed. In FIG. 37, transmission baseband frequency source 3601generates operating frequency signal 3602.

Then serial/parallel conversion sections 202 and 212, and inversediscrete Fourier transform sections 204 and 214, perform signalprocessing in synchronization with operating frequency signal 3602.

Similarly, radio section frequency source 3603 generates operatingfrequency signal 3604.

Then radio sections 206 and 216 perform frequency conversion ofpost-inverse-discrete-Fourier-transform signals 205 and 215 insynchronization with operating frequency signal 3604, and outputtransmit signals 207 and 217.

Thus, according to a transmitting apparatus of this embodiment,frequency sources can be reduced compared with a case in which afrequency source is provided individually for each antenna. Also,sharing frequency sources in the transmitting apparatus enables channelA and channel B signal frequency synchronization and timesynchronization to be performed easily in the receiving apparatus. Thisis because, since frequency sources are shared by channel A and channelB, individual synchronization is not necessary.

The receiving side will now be described. FIG. 38 is a block diagramshowing an example of the configuration of a receiving apparatusaccording to Embodiment 8 of the present invention. Parts in FIG. 38identical to those in FIG. 4 are assigned the same reference numerals asin FIG. 4, and detailed descriptions thereof are omitted.

A frequency source 3701 generates a reception baseband operatingfrequency signal 3702, and outputs operating frequency signal 3702 tosynchronization section 334.

A frequency source 3703 generates a radio section operating frequencysignal 3704, and outputs radio section operating frequency signal 3704to radio section 303 and radio section 313.

The operation of the receiving apparatus in FIG. 38 will now bedescribed.

Reception baseband frequency source 3701 generates operating frequencysignal 3702.

Synchronization section 334 compares operating frequency signal 3702 andthe synchronization timing acquired by means of received quadraturebaseband signals 304 and 314, and generates timing signal 335

Using frequency offset estimation signal 333, frequency source 3703controls the frequency so as to be synchronized with the transmittingapparatus, and generates operating frequency signal 3704.

Radio sections 303 and 313 perform frequency conversion of receivedsignals 302 and 312 respectively based on operating frequency signal3704.

Thus, according to a receiving apparatus of this embodiment, frequencysources can be reduced compared with a case in which a frequency sourceis provided individually for each antenna. Also, channel A and channel Bsignal frequency synchronization and time synchronization can beperformed easily.

A transmitting apparatus and receiving apparatus are not limited to theconfigurations in FIG. 37 and FIG. 38. Also, the use of multiplex framesand non-multiplexed frames with two channels and two antennas has beendescribed as an example, but the present invention is not limited tothis. For example, it is possible to implement the present inventionsimilarly with multiplex frames using three channels and three antennas,and multiplex frames using two channels and two of three antennas. Also,an example has been described in which OFDM is used as the communicationmethod, but it is possible to implement the present invention similarlywith a multicarrier method, a spread spectrum communication method, or asingle-carrier method. Moreover, a spread spectrum communication methodmay be used as the method for each carrier in a multicarrier system.Thus, it is possible to implement the present invention similarly withOFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

By using a transmitting apparatus provided with one transmissionbaseband frequency source and one radio section frequency source, and areceiving apparatus provided with one reception baseband frequencysource and one radio section frequency source, in a transmission methodwhereby modulated signals of a plurality of channels are transmittedfrom a plurality of antennas in the same frequency band, as describedabove, frequency sources can be reduced compared with a case in which afrequency source is provided individually for each antenna in thetransmitting apparatus. Also, sharing frequency sources in thetransmitting apparatus enables channel A and channel B signal frequencysynchronization and time synchronization to be performed easily in thereceiving apparatus.

Embodiment 9

In Embodiment 9 of the present invention, a description is given of acommunication method whereby the communication method is switchedbetween a communication method in which signals of a plurality ofchannels are transmitted from a plurality of antennas and acommunication method in which a signal of one channel is transmitted,according to the environment, and the configurations of an associatedtransmitting apparatus and receiving apparatus.

FIG. 39 is a drawing showing an example of base station arrangementaccording to Embodiment 9 of the present invention. In FIG. 39, basestation 3801 transmits a modulated signal at frequency f1, and thecorresponding communication limit is indicated by reference numeral3802. Similarly, base station 3803 transmits a modulated signal atfrequency f2, and the corresponding communication limit is indicated byreference numeral 3804. In FIG. 39, it is assumed that base station 3801that transmits a modulated signal at frequency f1 and base station 3803that transmits a modulated signal at frequency f2 are installed atalmost the same location.

A base station apparatus and communication terminal of this embodimentadaptively switch between signals of a communication method wherebysignals of a plurality of channels are multiplexed using a plurality ofantennas and a signal of a single channel according to the radio wavepropagation environment and communication area.

Base station 3801 transmits signals with the frame configurations shownin FIG. 9 at frequency f1.

Base station 3803 transmits signals with the frame configuration shownin FIG. 10 at frequency f2. Frequency f1 and frequency f2 are arrangedas shown in FIG. 11.

It is here assumed that base station 3801 is configured as shown in FIG.3, and that signals of a plurality of channels are multiplexed andtransmitted from a plurality of antennas. Here, for example, signals oftwo channels are multiplexed and transmitted using frame configurationssuch as shown in FIG. 9.

The receiving apparatus of base station 3801 will now be described indetail. FIG. 40 is a block diagram showing the configuration of a basestation receiving apparatus according to Embodiment 9 of the presentinvention. FIG. 40 shows one example of the configuration of a receivingapparatus of base station 3801 and base station 3803. In FIG. 40, aradio section 3903 converts a received signal 3902 received by areceiving antenna 3901, and outputs a received quadrature basebandsignal 3904 to a demodulation section 3905.

Demodulation section 3905 demodulates received quadrature basebandsignal 3904, and outputs a received digital signal 3906.

The transmitting apparatus of base station 3801 will now be described indetail. FIG. 41 is a block diagram showing the configuration of a basestation transmitting apparatus according to Embodiment 9 of the presentinvention. FIG. 41 shows one example of the configuration of atransmitting apparatus of base station 3803 according to thisembodiment. In FIG. 41, a serial/parallel conversion section 4002configures a frame from a transmit digital signal 4001, and outputs aparallel signal 4003 to an inverse discrete Fourier transform section4004.

Inverse discrete Fourier transform section 4004 performs inverse Fouriertransform processing of parallel signal 4003, and outputs apost-inverse-Fourier-transform signal 4005 to a radio section 4006.

Radio section 4006 converts post-inverse-Fourier-transform signal 4005to radio frequency, and a transmit signal 4007 is output as a radio wavefrom an antenna 4008.

FIG. 42 is a drawing showing an example of the configuration of aterminal receiving apparatus according to Embodiment 9 of the presentinvention. Parts in FIG. 42 identical to those in FIG. 13 or FIG. 14 areassigned the same reference numerals as in FIG. 13 or FIG. 14, anddetailed descriptions thereof are omitted. The receiving apparatus inFIG. 42 comprises a receiving section for demodulating frequency f1channel A and channel B via two antennas, and a receiving section fordemodulating frequency f2 channel C.

Radio wave propagation environment estimation section 1301 estimates theradio wave propagation environments of frequency f1 channel A andchannel B multiplex signals, and outputs a radio wave propagationenvironment estimation signal 1302.

Radio wave propagation environment estimation section 1303 estimates theradio wave propagation environment of a frequency f2 channel C signal,and outputs a radio wave propagation environment estimation signal 1304.

A communication method determination section 4101 decides upon eithercommunication by means of frequency f1—that is, with base station3801—or communication by means of frequency f2—that is, with basestation 3803—based on radio wave propagation environment estimationsignals 1302 and 1304.

FIG. 43 is a drawing showing an example of the configuration of aterminal transmitting apparatus according to Embodiment 9 of the presentinvention. The transmitting apparatus in FIG. 43 comprises a frequencyf1 modulated signal transmitting section and a frequency f2 modulatedsignal transmitting section.

A communication method selection section 4203 has a determinedcommunication method signal 4202 as input, and outputs a transmitdigital signal 4201 to a modulated signal generation section 4205 ormodulated signal generation section 4211 according to the communicationmethod contained in determined communication method signal 4202. That isto say, when transmitting by means of frequency f1, communication methodselection section 4203 outputs transmit digital signal 4201 to modulatedsignal generation section 4205 as a frequency f1 transmit digital signal4204, and when transmitting by means of frequency f2, communicationmethod selection section 4203 outputs transmit digital signal 4201 tomodulated signal generation section 4211 as a frequency f2 transmitdigital signal 4210.

Modulated signal generation section 4205 modulates frequency f1 transmitdigital signal 4204, and outputs a transmit quadrature baseband signal4206 to a radio section 4207.

Radio section 4207 converts transmit quadrature baseband signal 4206 toradio frequency f1, and a frequency f1 modulated signal 4208 istransmitted as a radio wave from an antenna 4209.

Modulated signal generation section 4211 modulates frequency f2 transmitdigital signal 4210, and outputs a transmit quadrature baseband signal4212 to a radio section 4213.

Radio section 4213 converts transmit quadrature baseband signal 4212 toradio frequency f2, and a frequency f2 modulated signal 4214 istransmitted as a radio wave from an antenna 4215.

FIG. 44 is a drawing showing an example of base station arrangementaccording to Embodiment 9 of the present invention. Parts in FIG. 44identical to those in FIG. 39 are assigned the same reference numeralsas in FIG. 39, and detailed descriptions thereof are omitted.

As in FIG. 39, at point A and point D, a modulated signal transmitted bybase station 3801 that transmits a frequency f1 modulated signal can bereceived, and at point B and point C, a modulated signal transmitted bybase station 3803 that transmits a frequency f2 modulated signal can bereceived.

At this time, it is assumed that a terminal is at point A or D, forexample. Then, a signal whereby it is known that a frequency f1 signalis present is output as radio wave propagation environment estimationsignal 1302 by radio wave propagation environment estimation section1301 of the terminal receiving apparatus in FIG. 42, and a signalindicating that a frequency f2 signal is not present is output as radiowave propagation environment estimation signal 1304 by radio wavepropagation environment estimation section 1303.

It is also assumed that a terminal is at point B or C. Then, a signalwhereby it is known that a frequency f1 signal is not present is outputas radio wave propagation environment estimation signal 1302 by radiowave propagation environment estimation section 1301 of the terminalreceiving apparatus in FIG. 42, and a signal indicating that a frequencyf2 signal is present is output as radio wave propagation environmentestimation signal 1304 by radio wave propagation environment estimationsection 1303.

Communication method determination section 4101 has above-describedradio wave propagation environment estimation signals 1302 and 1304 asinput, decides upon communication by frequency f1 or f2 for which amodulated signal is present, and outputs the decision as a determinedcommunication method signal 4102.

When there is a base station 3801 that transmits a frequency f1modulated signal and a base station 3803 that transmits a frequency f2modulated signal, as in FIG. 44, a signal whereby it is known that afrequency f1 signal is present is output as radio wave propagationenvironment estimation signal 1302 by radio wave propagation environmentestimation section 1301, and a signal indicating that a frequency f2signal is present is also output as radio wave propagation environmentestimation signal 1304 by radio wave propagation environment estimationsection 1303.

Communication method determination section 4101 in FIG. 42 hasabove-described radio wave propagation environment estimation signals1302 and 1304 as input, selects a communication method with a hightransmission speed, for example, and outputs determined communicationmethod signal 4102. If the occupied frequency bands of f1 and f2modulated signals are equal at this time, since the communication speedis higher with frequency f1 whereby signals of a plurality of channelsare transmitted by a plurality of antennas, the frequency f1communication method is selected as the preferred method.

If a terminal wishes to select an error-tolerant communication method,the frequency f2 communication method is selected as the preferredmethod.

The configurations of the above transmitting apparatus and receivingapparatus are not limited to the configurations in FIG. 3, FIG. 40, FIG.41, FIG. 42, or FIG. 43. Also, in the frame configurations in FIG. 9,multiplex frames with two channels and two antennas have beenillustrated, but the present invention is not limited to this. Forexample, it is possible to transmit multiplex frames using threechannels and three antennas. Also, an example has been described inwhich OFDM is used as the communication method, but it is possible toimplement the present invention similarly with a multicarrier method, aspread spectrum communication method, or a single-carrier method. Forexample, OFDM may be used as a communication method whereby signals of aplurality of channels are transmitted by a plurality of antennas, and aspread spectrum communication method as a non-multiplexed signalcommunication method. Moreover, a spread spectrum communication methodmay be used as the method for each carrier in a multicarrier system.Thus, it is possible to implement the present invention similarly withOFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, by having a terminal switch the communication method tobe selected, giving priority to transmission speed or giving priority toerror tolerance, by using a communication method whereby thecommunication method is switched between a communication method in whichsignals of a plurality of channels are transmitted from a plurality ofantennas and a communication method in which a signal of one channel istransmitted, it is possible for a terminal to perform communication asdesired. Also, according to a transmitting apparatus and receivingapparatus of this embodiment, by switching the communication methodaccording to the radio wave propagation environment, it is possible toachieve compatibility between data transmission speed and received dataquality.

Embodiment 10

In Embodiment 10 of the present invention, a description is given of acommunication method whereby a radio communication apparatus thatreceives information on the number of antennas provided from acommunicating party, is provided with a plurality of antennas, and has afunction that transmits a plurality of channels, transmits modulatedsignals of a number of channels in accordance with information on thenumber of antennas.

FIG. 45 is a drawing showing an example of base station frameconfigurations according to Embodiment 10 of the present invention.Parts in FIG. 45 identical to those in FIG. 2 are assigned the samereference numerals as in FIG. 2, and detailed descriptions thereof areomitted. In FIG. 45, reference numeral 4401 indicates a guard symbol,where there is no modulated symbol. Also, in FIG. 45, modulated signalsof 1 to 3 channels are transmitted.

FIG. 46 is a drawing showing an example of base station frameconfigurations according to Embodiment 10 of the present invention.Parts in FIG. 46 identical to those in FIG. 2 or FIG. 45 are assignedthe same reference numerals as in FIG. 2 or FIG. 45, and detaileddescriptions thereof are omitted. In FIG. 45, modulated signals of 1 to2 channels are transmitted.

FIG. 47 is a drawing showing an example of the configuration of a basestation transmitting apparatus according to Embodiment 10 of the presentinvention. In FIG. 47, a modulated signal generation section 4602modulates a channel A transmit digital signal 4601, configures a frameindicated by a frame configuration signal 4619, and outputs a modulatedsignal 4603 with a frame configuration in accordance with frameconfiguration signal 4619 to a radio section 4604.

Radio section 4604 converts modulated signal 4603 to radio frequency,and a transmit signal 4605 is output as a radio wave from an antenna4606.

A modulated signal generation section 4608 modulates a channel Btransmit digital signal 4607, configures a frame indicated by frameconfiguration signal 4619, and outputs a modulated signal 4609 with aframe configuration in accordance with frame configuration signal 4619to a radio section 4610.

Radio section 4610 converts modulated signal 4609 to radio frequency,and a transmit signal 4611 is output as a radio wave from an antenna4612.

A modulated signal generation section 4614 modulates a channel Ctransmit digital signal 4613, configures a frame indicated by frameconfiguration signal 4619, and outputs a modulated signal 4615 with aframe configuration in accordance with frame configuration signal 4619to a radio section 4616.

Radio section 4616 converts modulated signal 4615 to radio frequency,and a transmit signal 4617 is output as a radio wave from an antenna4618.

By this means, modulated signals of three channels are multiplexed andtransmitted at the same frequency.

FIG. 48 is a drawing showing an example of the configuration of a basestation receiving apparatus according to Embodiment 10 of the presentinvention. Parts in FIG. 48 identical to those in FIG. 40 are assignedthe same reference numerals as in FIG. 40, and detailed descriptionsthereof are omitted.

A data separation section 4701 separates a received digital signal 3906into receive data, antenna information, and radio wave propagationenvironment estimation information, outputs receive data 4702, andoutputs an antenna information signal 4703 and radio wave propagationenvironment estimation information signal 4704 to a frame configurationdetermination section 4705.

Frame configuration determination section 4705 determines the frameconfiguration based on antenna information signal 4703 and radio wavepropagation environment estimation information signal 4704, and outputsa frame configuration signal 4706.

FIG. 49 is a drawing showing an example of the configuration of aterminal receiving apparatus according to Embodiment 10 of the presentinvention. In FIG. 49, a radio section 4803 converts a received signal4802 received by an antenna 4801 to baseband frequency, and outputs areceived quadrature baseband signal 4804 to a channel distortionestimation section 4805, channel distortion estimation section 4807, andchannel distortion estimation section 4809.

Channel distortion estimation section 4805 outputs a channel A channeldistortion estimation signal 4806 from received quadrature basebandsignal 4804 to a signal processing section 4831.

Channel distortion estimation section 4807 outputs a channel B channeldistortion estimation signal 4808 from received quadrature basebandsignal 4804 to signal processing section 4831.

Channel distortion estimation section 4809 outputs a channel C channeldistortion estimation signal 4810 from received quadrature basebandsignal 4804 to signal processing section 4831.

A radio section 4813 converts a received signal 4812 received by anantenna 4811 to baseband frequency, and outputs a received quadraturebaseband signal 4814 to a channel distortion estimation section 4815,channel distortion estimation section 4817, and channel distortionestimation section 4819.

Channel distortion estimation section 4815 has received quadraturebaseband signal 4814 as input, and outputs a channel A channeldistortion estimation signal 4816 to signal processing section 4831.

Channel distortion estimation section 4817 has received quadraturebaseband signal 4814 as input, and outputs a channel B channeldistortion estimation signal 4818 to signal processing section 4831.

Channel distortion estimation section 4819 has received quadraturebaseband signal 4814 as input, and outputs a channel C channeldistortion estimation signal 4820 to signal processing section 4831.

A radio section 4823 has a received signal 4822 received by an antenna4821 as input, and outputs a received quadrature baseband signal 4824 toa channel distortion estimation section 4825, channel distortionestimation section 4827, and channel distortion estimation section 4829.

Channel distortion estimation section 4825 has received quadraturebaseband signal 4824 as input, and outputs a channel A channeldistortion estimation signal 4826 to signal processing section 4831.

Channel distortion estimation section 4827 has received quadraturebaseband signal 4824 as input, and outputs a channel B channeldistortion estimation signal 4828 to signal processing section 4831.

Channel distortion estimation section 4829 has received quadraturebaseband signal 4824 as input, and outputs a channel C channeldistortion estimation signal 4830 to signal processing section 4831.

Signal processing section 4831 has received quadrature baseband signals4804, 4814, and 4824, channel A channel distortion estimation signals4806, 4816, and 4826, channel B channel distortion estimation signals4808, 4818, and 4828, and channel C channel distortion estimationsignals 4810, 4820, and 4830 as input, performs inverse matrixcomputations, and outputs a channel A received quadrature basebandsignal 4832 to a demodulation section 4833, a channel B receivedquadrature baseband signal 4835 to a demodulation section 4836, and achannel C received quadrature baseband signal 4838 to a demodulationsection 4839.

Demodulation section 4833 demodulates channel A received quadraturebaseband signal 4832, and outputs a received digital signal 4834.

Demodulation section 4836 demodulates channel B received quadraturebaseband signal 4835, and outputs a received digital signal 4837.

Demodulation section 4839 demodulates channel C received quadraturebaseband signal 4838, and outputs a received digital signal 4840.

A radio wave propagation environment estimation section 4841 estimatesthe radio wave propagation environment from received quadrature basebandsignals 4804, 4814, and 4824, and outputs a radio wave propagationenvironment estimation signal 4842.

FIG. 50 is a drawing showing an example of the configuration of aterminal transmitting apparatus according to Embodiment 10 of thepresent invention. In FIG. 50, a data generation section 4904 generatesa transmit digital signal 4905 from transmit data 4901, antennainformation 4902, which is information on the number of antennas theterminal has for receiving, and radio wave propagation environmentestimation signal 4903, and outputs transmit digital signal 4905 to amodulated signal generation section 4906.

Modulated signal generation section 4906 modulates transmit digitalsignal 4905, and outputs a transmit quadrature baseband signal 4907 to aradio section 4908.

Radio section 4908 converts transmit quadrature baseband signal 4907 toradio frequency, and a transmit signal 4909 is output as a radio wavefrom an antenna 4910.

FIG. 51 is a drawing showing an example of the frame configuration of amodulated signal transmitted by a terminal according to Embodiment 10 ofthe present invention. In FIG. 51, reference numeral 5001 indicatesantenna information symbols, reference numeral 5002 indicates radio wavepropagation environment symbols, and reference numeral 5003 indicatesdata symbols.

FIG. 52 is a drawing showing an example of the configuration of aterminal receiving apparatus according to Embodiment 10 of the presentinvention. Parts in FIG. 52 identical to those in FIG. 4 or FIG. 30 areassigned the same reference numerals as in FIG. 4 or FIG. 30, anddetailed descriptions thereof are omitted.

In FIG. 52, a radio wave propagation environment estimation section 5101estimates the radio wave propagation environment frompost-Fourier-transform signals 306 and 316, and outputs a radio wavepropagation environment estimation signal 5102.

Using FIG. 45, FIG. 46, FIG. 47, FIG. 48, FIG. 49, FIG. 50, FIG. 51, andFIG. 52, a description will now be given of a communication methodwhereby a radio communication apparatus that receives information on thenumber of antennas provided from a communicating party, is provided witha plurality of antennas, and has a function that transmits a pluralityof channels, transmits modulated signals of a number of channels inaccordance with information on the number of antennas.

The configuration of a terminal that can receive three channels isdescribed below.

FIG. 49 shows a terminal receiving apparatus that can receive signals ofchannels A, B, and C. FIG. 50 shows the terminal transmitting apparatus,in which data generation section 4904 has, as input, transmit data 4901,antenna information 4902, which is information indicating that threeantennas are provided or that 3-channel multiplex signals can bereceived, and a radio wave propagation environment estimation signal4903, and outputs transmit digital signal 4905 in accordance with theframe configuration in FIG. 51. At this time, radio wave propagationenvironment estimation signal 4903 in FIG. 50 corresponds to radio wavepropagation environment estimation signal 4842 in FIG. 49.

FIG. 52 shows a terminal receiving apparatus that can receive signals ofchannels A and B. FIG. 50 shows the terminal transmitting apparatus, inwhich data generation section 4904 has, as input, transmit data 4901,antenna information 4902, which is information indicating that twoantennas are provided or that 2-channel multiplex signals can bereceived, and a radio wave propagation environment estimation signal4903, and outputs transmit digital signal 4905 in accordance with theframe configuration in FIG. 51. At this time, radio wave propagationenvironment estimation signal 4903 in FIG. 50 corresponds to radio wavepropagation environment estimation signal 5102 in FIG. 52.

The configuration of a base station will now be described.

FIG. 48 shows a base station receiving apparatus. At this time, it isassumed that, for example, communication is being performed with aterminal capable of demodulating channels A, B, and C as shown in FIG.49. Data separation section 4701 has a received digital signal as input,separates data transmitted from the terminal with the frameconfiguration in FIG. 51, and outputs receive data 4702, antennainformation signal 4703, and radio wave propagation environmentestimation information signal 4704. Here, antenna information signal4703 is information indicating that three antennas are provided or that3-channel multiplex signals can be received.

Frame configuration determination section 4705 has antenna informationsignal 4703 and radio wave propagation environment estimationinformation signal 4704 as input, determines frame configurations basedon antenna information signal 4703 and radio wave propagationenvironment estimation information signal 4704, and outputs frameconfiguration signal 4706. Here, the frame configurations based onantenna information signal 4703 indicating that three antennas areprovided or that 3-channel multiplex signals can be received are asshown in FIG. 45.

In FIG. 45, since the terminal that is the communicating party canreceive three channels, when radio wave propagation environmentestimation information signal 4704 indicates that the radio wavepropagation environment is good, signals of three channels aremultiplexed and transmitted, as at times 3, 6, 7, and 10, for example.When the radio wave propagation environment is fair, signals of twochannels are multiplexed and transmitted, as at times 4 and 5. When theradio wave propagation environment is poor, a signal of one channel istransmitted, as at times 8 and 9.

The base station transmitting apparatus in FIG. 47 transmits modulatedsignals based on FIG. 45 frame configurations contained in frameconfiguration signal 4619.

Next, the situation when communication is performed with a terminalcapable of modulating channels A and B will be described.

In the base station receiving apparatus in FIG. 48, data separationsection 4701 has a received digital signal as input, separates datatransmitted from the terminal with the frame configuration in FIG. 51,and outputs receive data 4702, antenna information signal 4703, andradio wave propagation environment estimation information signal 4704.Here, antenna information signal 4703 is information indicating that twoantennas are provided or that 2-channel multiplex signals can bereceived.

Frame configuration determination section 4705 has antenna informationsignal 4703 and radio wave propagation environment estimationinformation signal 4704 as input, determines frame configurations basedon antenna information signal 4703 and radio wave propagationenvironment estimation information signal 4704, and outputs frameconfiguration signal 4706. Here, the frame configurations based onantenna information signal 4703 indicating that two antennas areprovided or that 2-channel multiplex signals can be received are asshown in FIG. 46.

In FIG. 46, since the terminal that is the communicating party canreceive two channels, when radio wave propagation environment estimationinformation signal 4704 indicates that the radio wave propagationenvironment is good, signals of two channels are multiplexed andtransmitted, as at times 3, 4, 5, 7, and 10, for example. When the radiowave propagation environment is poor, a signal of one channel istransmitted, as at times 6, 8, and 9.

The base station transmitting apparatus in FIG. 47 transmits modulatedsignals based on FIG. 46 frame configurations contained in frameconfiguration signal 4619.

The configurations of the transmitting apparatus and receiving apparatusabove are not limited to the configurations in FIG. 47, FIG. 48, FIG.49, FIG. 50, or FIG. 52. Also, in FIG. 47, a configuration has beenillustrated that has three antennas and is capable of multiplexing threechannels, but the present invention is not limited to this. Furthermore,an example has been described in which OFDM is used as the communicationmethod, but it is possible to implement the present invention similarlywith a multicarrier method, a spread spectrum communication method, or asingle-carrier method. Moreover, a spread spectrum communication methodmay be used as the method for each carrier in a multicarrier system.Thus, it is possible to implement the present invention similarly withOFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, by dynamically changing the number of multiplexchannels by using a communication method whereby a radio communicationapparatus that receives information on the number of antennas providedfrom a communicating party, is provided with a plurality of antennas,and has a function that transmits a plurality of channels, transmitsmodulated signals of a number of channels in accordance with informationon the number of antennas, it is possible to achieve compatibilitybetween data transmission speed and received data quality.

Embodiment 11

In Embodiment 11 of the present invention, a description is given of acommunication method whereby, in a communication method in whichmodulated signals of a plurality of channels are transmitted from aplurality of antennas, the first channel is used as a pilot channel, thepilot channel modulation method is changed to one or another PSKmodulation method according to the radio wave propagation environment orthe like, and the modulation method for other than the first channel ischanged to one or another modulation method according to the radio wavepropagation environment or the like.

Using FIG. 3, FIG. 19, FIG. 27, FIG. 29, FIG. 48, FIG. 50, and FIG. 52,a description will now be given of a communication method whereby, in acommunication method in which modulated signals of a plurality ofchannels are transmitted from a plurality of antennas, the first channelis used as a pilot channel, the pilot channel modulation method ischanged to one or another PSK modulation method according to the radiowave propagation environment or the like, and the modulation method forother than the first channel is changed to one or another modulationmethod according to the radio wave propagation environment or the like.

The configuration of a terminal receiving apparatus is as shown in FIG.52, in which radio wave propagation environment estimation section 5101estimates the radio wave propagation environment frompost-Fourier-transform signals 306 and 316, and outputs a radio wavepropagation environment estimation signal.

The configuration of a terminal transmitting apparatus is as shown inFIG. 50, in which data generation section 4904 has transmit data 4901,antenna information 4902, and a radio wave propagation environmentestimation signal 4903 as input, and configures and outputs transmitdigital signal 4905 in accordance with the frame configuration in FIG.51. At this time, radio wave propagation environment estimation signal4903 corresponds to radio wave propagation environment estimation signal5102 in FIG. 52.

The configuration of a base station receiving apparatus is as shown inFIG. 48, in which data separation section 4701 separates receiveddigital signal 3906 into receive data 4702, antenna information signal4703, and radio wave propagation environment estimation informationsignal 4704 in accordance with the frame configuration in FIG. 51, andoutputs receive data 4702, antenna information signal 4703, and radiowave propagation environment estimation information signal 4704. Frameconfiguration determination section 4705 has antenna information signal4703 and radio wave propagation environment estimation informationsignal 4704 as input, and changes the modulation method in accordancewith radio wave propagation environment estimation information signal4704, for example.

At this time, if channel A is a pilot channel in the FIG. 19, FIG. 27,or FIG. 29 frame configurations, a modulation method change is performedonly for channel B. This is because, when channel B is demodulated, itis demodulated based on a channel A signal, and therefore it ispreferable for the channel A modulation method to be fixed.

Alternatively, the modulation methods to which a change can be made forchannel B are not limited, but the modulation method to which a changecan be made for channel A is limited to a PSK method. This is becausePSK modulation has no amplitude fluctuations, and it is thereforepossible to demodulate channel B.

Also, communication control can be performed accurately by transmittingimportant information for performing communication control by means ofchannel A PSK modulation. For example, it is possible to use PSKmodulation only for channel A for this purpose, transmit data by meansof channel B, and change the modulation method in order to achievecompatibility between data transmission speed and received data quality.

The configurations of the transmitting apparatus and receiving apparatusabove are not limited to the configurations in FIG. 3, FIG. 48, FIG. 50,or FIG. 52. Also, in the frame configurations in FIG. 19, FIG. 27,multiplex frames with two channels and two antennas have beenillustrated, but the present invention is not limited to this. Forexample, it is possible for the transmitting apparatus to transmitmultiplex frames using three channels and three antennas. Also, anexample has been described in which OFDM is used as the communicationmethod, but it is possible to implement the present invention similarlywith a multicarrier method, a spread spectrum communication method, or asingle-carrier method, and a spread spectrum communication method may beused as the method for each carrier in a multicarrier system. Thus, itis possible to implement the present invention similarly with OFDM-CDM.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, by changing the modulation method according to theradio wave propagation environment by using a communication methodwhereby, in a communication method in which modulated signals of aplurality of channels are transmitted from a plurality of antennas, thefirst channel is used as a pilot channel, the pilot channel modulationmethod is changed to one or another PSK modulation method according tothe radio wave propagation environment or the like, and the modulationmethod for other than the first channel is changed to one or anothermodulation method according to the radio wave propagation environment orthe like, it is possible to achieve compatibility between datatransmission speed and received data quality.

Embodiment 12

In Embodiment 12 of the present invention, a description is given of amethod whereby an antenna to be used for transmission is selected basedon radio wave propagation environment estimation information from thecommunicating party, and a method whereby an antenna to be used forreception by the communicating party is determined based on radio wavepropagation environment information from the communicating party, andreported to the communicating party.

FIG. 53 is showing an example of base station transmit signal frameconfigurations according to Embodiment 12 of the present invention.Parts in FIG. 53 identical to those in FIG. 2 or FIG. 45 are assignedthe same reference numerals as in FIG. 2 or FIG. 45, and detaileddescriptions thereof are omitted.

FIG. 54 is a drawing showing an example of the configuration of aterminal receiving apparatus according to Embodiment 12 of the presentinvention. Parts in FIG. 54 identical to those in FIG. 49 are assignedthe same reference numerals as in FIG. 49, and detailed descriptionsthereof are omitted.

Using received quadrature baseband signal 4804, a channel distortionestimation section 5301 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 1, and outputs atransmitting antenna 1 channel distortion estimation signal 5302 to aradio wave propagation environment estimation section 4841.

Using received quadrature baseband signal 4804, a channel distortionestimation section 5303 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 2, and outputs atransmitting antenna 2 channel distortion estimation signal 5304 toradio wave propagation environment estimation section 4841.

Using received quadrature baseband signal 4804, a channel distortionestimation section 5305 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 3, and outputs atransmitting antenna 3 channel distortion estimation signal 5306 toradio wave propagation environment estimation section 4841.

Using received quadrature baseband signal 4814, a channel distortionestimation section 5307 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 1, and outputs atransmitting antenna 1 channel distortion estimation signal 5308 toradio wave propagation environment estimation section 4841.

Using received quadrature baseband signal 4814, a channel distortionestimation section 5309 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 2, and outputs atransmitting antenna 2 channel distortion estimation signal 5310 toradio wave propagation environment estimation section 4841.

Using received quadrature baseband signal 4814, a channel distortionestimation section 5311 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 3, and outputs atransmitting antenna 3 channel distortion estimation signal 5312 toradio wave propagation environment estimation section 4841.

Using received quadrature baseband signal 4824, a channel distortionestimation section 5313 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 1, and outputs atransmitting antenna 1 channel distortion estimation signal 5314 toradio wave propagation environment estimation section 4841.

Using received quadrature baseband signal 4824, a channel distortionestimation section 5315 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 2, and outputs atransmitting antenna 2 channel distortion estimation signal 5316 toradio wave propagation environment estimation section 4841.

Using received quadrature baseband signal 4824, a channel distortionestimation section 5317 estimates channel distortion of a transmitsignal transmitted from transmitting antenna 3, and outputs atransmitting antenna 3 channel distortion estimation signal 5318 toradio wave propagation environment estimation section 4841.

Radio wave propagation environment estimation section 4841 estimates theradio wave propagation environment from transmitting antenna 1 channeldistortion estimation signals 5302, 5308, and 5314, transmitting antenna2 channel distortion estimation signals 5304, 5310, and 5316, andtransmitting antenna 3 channel distortion estimation signals 5306, 5312,and 5318, and outputs the result as radio wave propagation environmentestimation information signal 4842.

An antenna selection section 5319 has received quadrature basebandsignals 4804, 4814, and 4824 as input, selects input from an antenna tobe used for demodulation, and outputs this as antenna selection signal5320.

FIG. 55 is a drawing showing an example of the configuration of aterminal transmitting apparatus according to Embodiment 12 of thepresent invention. Parts in FIG. 55 identical to those in FIG. 50 areassigned the same reference numerals as in FIG. 50, and detaileddescriptions thereof are omitted.

FIG. 56 is a drawing showing an example of the frame configuration of amodulated signal transmitted by a terminal according to this embodiment.In FIG. 56, reference numeral 5501 indicates channel distortionestimation symbols from transmitting antenna 1, reference numeral 5502indicates channel distortion estimation symbols from transmittingantenna 2, reference numeral 5503 indicates channel distortionestimation symbols from transmitting antenna 3, and reference numeral5504 indicates data symbols.

FIG. 57 is a drawing showing an example of the configuration of a basestation transmitting apparatus according to Embodiment 11 of the presentinvention. Parts in FIG. 57 identical to those in FIG. 47 are assignedthe same reference numerals as in FIG. 47, and detailed descriptionsthereof are omitted. Reference numeral 5602 indicates antennainformation used by a terminal for reception.

An antenna selection section 5601 outputs transmit signals 4605 and 4611as radio waves from antenna 4606, 4612, or 4618, in accordance with theframe configuration indicated by frame configuration signal 4619.

FIG. 58 is a drawing showing an example of the configuration of a basestation receiving apparatus according to Embodiment 12 of the presentinvention. A used antenna determination section 5701 has radio wavepropagation environment estimation information signal 4704 as input, andoutputs frame configuration signal 4706 and antenna information 5702used by a terminal for reception.

FIG. 59 is a drawing showing an example of the configuration of a basestation transmitting apparatus according to Embodiment 12 of the presentinvention. Parts in FIG. 59 identical to those in FIG. 47 are assignedthe same reference numerals as in FIG. 47, and detailed descriptionsthereof are omitted.

In FIG. 59, a modulated signal generation section 5804 has a channel Atransmit digital signal 5801, channel B transmit digital signal 5802,antenna information 5803 used by a terminal for reception, and frameconfiguration information 4619 as input, and generates and outputstransmit quadrature baseband signals 4603, 4609, and 4615 in accordancewith frame configuration information 4619.

Using FIG. 53, FIG. 54, FIG. 55, FIG. 56, FIG. 57, FIG. 58, and FIG. 59,a description will now be given of a method whereby an antenna to beused for transmission is selected based on radio wave propagationenvironment estimation information from the communicating party, and amethod whereby an antenna to be used for reception by the communicatingparty is determined based on radio wave propagation environmentinformation from the communicating party, and reported to thecommunicating party.

For example, in order to estimate the radio wave propagation environmentin a terminal receiving apparatus, the base station transmittingapparatus in FIG. 57 or FIG. 59 transmits estimation symbols 103 as intimes 1, 2, and 3, and times 11, 12, and 13, in FIG. 53.

Then, transmitting antenna 1 channel distortion estimation section 5301of the terminal receiving apparatus in FIG. 54 has received quadraturebaseband signal 4804 as input, estimates channel distortion of a signaltransmitted from antenna 1—that is, antenna 4606—in FIG. 47 from time 1and 11 estimation symbols 103, and outputs transmitting antenna 1channel distortion estimation signal 5302.

Similarly, transmitting antenna 1 channel distortion estimation section5307 of the receiving apparatus has received quadrature baseband signal4814 as input, estimates channel distortion of a signal transmitted fromantenna 1—that is, antenna 4606—in FIG. 47 from time 1 and 11 estimationsymbols 103, and outputs transmitting antenna 1 channel distortionestimation signal 5208.

Similarly, transmitting antenna 1 channel distortion estimation section5313 of the receiving apparatus has received quadrature baseband signal4824 as input, estimates channel distortion of a signal transmitted fromantenna 1—that is, antenna 4606—in FIG. 47 from time 1 and 11 estimationsymbols 103, and outputs transmitting antenna 1 channel distortionestimation signal 5214.

Transmitting antenna 2 channel distortion estimation section 5303 of thereceiving apparatus has received quadrature baseband signal 4804 asinput, estimates channel distortion of a signal transmitted from antenna2—that is, antenna 4612—in FIG. 47 from time 2 and 12 estimation symbols103, and outputs transmitting antenna 2 channel distortion estimationsignal 5304.

Similarly, transmitting antenna 2 channel distortion estimation section5309 of the receiving apparatus has received quadrature baseband signal4814 as input, estimates channel distortion of a signal transmitted fromantenna 2—that is, antenna 4612—in FIG. 47 from time 2 and 12 estimationsymbols 103, and outputs transmitting antenna 2 channel distortionestimation signal 5310.

Similarly, transmitting antenna 2channel distortion estimation section5315 of the receiving apparatus has received quadrature baseband signal4824 as input, estimates channel distortion of a signal transmitted fromantenna 2—that is, antenna 4612—in FIG. 59 from time 2 and 12 estimationsymbols 103, and outputs transmitting antenna 2 channel distortionestimation signal 5316.

Transmitting antenna 3 channel distortion estimation section 5305 of thereceiving apparatus has received quadrature baseband signal 4804 asinput, estimates channel distortion of a signal transmitted from antenna3—that is, antenna 4618—in FIG. 59 from time 3 and 13 estimation symbols103, and outputs transmitting antenna 3 channel distortion estimationsignal 5306.

Similarly, transmitting antenna 3 channel distortion estimation section5311 of the receiving apparatus has received quadrature baseband signal4814 as input, estimates channel distortion of a signal transmitted fromantenna 3—that is, antenna 4618—in FIG. 59 from time 3 and 13 estimationsymbols 103, and outputs transmitting antenna 3 channel distortionestimation signal 5312.

Similarly, transmitting antenna 3 channel distortion estimation section5317 of the receiving apparatus has received quadrature baseband signal4824 as input, estimates channel distortion of a signal transmitted fromantenna 3—that is, antenna 4618—in FIG. 59 from time 3 and 13 estimationsymbols 103, and outputs transmitting antenna 3 channel distortionestimation signal 5318.

Then, radio wave propagation environment estimation section 4841 hastransmitting antenna 1 channel distortion estimation signals 5302, 5308,and 5314, transmitting antenna 2 channel distortion estimation signals5304, 5310, and 5316, and transmitting antenna 3 channel distortionestimation signals 5306, 5312, and 5318 as input, and outputs radio wavepropagation environment estimation signal 4842.

FIG. 55 shows a terminal transmitting apparatus, in which datageneration section 4904 has transmit data 4901 and radio wavepropagation environment estimation signal 4903 as input, and outputstransmit digital signal 4905 in accordance with the frame configurationin FIG. 56. At this time, radio wave propagation environment estimationsignal 4903 corresponds to radio wave propagation environment estimationsignal 4842 in FIG. 54.

FIG. 58 shows a base station receiving apparatus, in which dataseparation section 4701 has transmit digital signal 4905 in accordancewith the frame configuration in FIG. 56 as input, separates this intodata and a radio wave propagation environment estimation signal, andoutputs receive data 4702 and radio wave propagation environmentestimation information signal 4704.

Used antenna determination section 5701 has radio wave propagationenvironment estimation information signal 4704 as input, determines anantenna to be used by the base station for transmitting a modulatedsignal based on radio wave propagation environment estimationinformation signal 4704, and outputs this as frame configuration signal4706. An antenna used by a terminal for reception is determined based onthe kind of frame configurations in FIG. 53 and radio wave propagationenvironment estimation information signal 4704, for example, and antennainformation 5702 used by a terminal for reception is output.

FIG. 59 shows an example of the configuration of a base stationtransmitting apparatus, in which modulated signal generation section5804 has channel A transmit digital signal 5801, channel B transmitdigital signal 5802, antenna information 5803 used by a terminal forreception, and frame configuration information 4619 as input, andoutputs transmit quadrature baseband signals 4603, 4609, and 4615—forexample, transmitting antenna information used by a terminal forreception at time 4 antenna 1 in FIG. 53, and transmitting modulatedsignals from antenna 1 and antenna 2 in times 5 to 10. At this time,frame configuration signal 4619 corresponds to frame configurationsignal 4706 in FIG. 58, and antenna information 5803 used by a terminalfor reception corresponds to antenna information 5702 used by a terminalfor reception in FIG. 58.

FIG. 57 shows a base station transmitting apparatus configuration thatdiffers from that in FIG. 59. In FIG. 57, antenna selection section 5601has transmit signals 4605 and 4611, and frame configuration signal 4619,as input, and selects output by antenna 1, antenna 2, or antenna 3, inaccordance with FIG. 53 frame configurations, and transmit signals 4605and 4611 are output as radio waves from antenna 1, antenna 2, or antenna3.

The configurations of the transmitting apparatus and receiving apparatusabove are not limited to the configurations in FIG. 48, FIG. 54, FIG.55, FIG. 57, or FIG. 59. Also, in the frame configurations in FIG. 53,FIG. 27, multiplex frames with two channels and three antennas have beenillustrated, but the present invention is not limited to this. Forexample, it is possible for the present invention to be similarlyimplemented with a transmitting apparatus transmitting multiplex framesusing three channels and four antennas. Also, an example has beendescribed in which OFDM is used as the communication method, but it ispossible to implement the present invention similarly with amulticarrier method, a spread spectrum communication method, or asingle-carrier method, and a spread spectrum communication method may beused as the method for each carrier in a multicarrier system. Thus, itis possible to implement the present invention similarly with OFDM-CDM.Moreover, an example of communication between one base station and oneterminal has been described, but it is possible to implement the presentinvention similarly for one base station and n terminals.

Furthermore, there are also cases where one antenna is composed of aplurality of antennas.

Thus, according to a transmitting apparatus and receiving apparatus ofthis embodiment, data received data quality is improved by selecting atransmitting/receiving antenna with the best multiplex signal separationprecision by using a method whereby an antenna to be used fortransmission is selected based on radio wave propagation environmentestimation information from the communicating party, and a methodwhereby an antenna to be used for reception by the communicating partyis determined based on radio wave propagation environment informationfrom the communicating party, and reported to the communicating party.

Embodiment 13

In Embodiment 13 of the present invention, a description is given of apilot symbol transmission method in a MIMO (Multi-Input Multi-Output)system in which modulated signals of a plurality of channels aretransmitted from a plurality of antennas at the same frequency, and arereceived by a plurality of antennas and demodulated.

In a MIMO system, when channel state information (CSI) is known not onlyin the receiving station but also on the transmitting side, acommunication method can be implemented whereby the transmitting stationtransmits a signal vectored using a transmission channel signaturevector to the receiving station from a transmitting array antenna, andthe receiving station detects the transmit signal using a receptionchannel signature vector corresponding to the transmission channelsignature vector from a received signal at a receiving array antenna,and demodulates the signal.

In particular, as a communication mode in which a plurality of channelsare configured and multiplex transmission of signals is performed in thecommunication space, there is an eigenmode that uses a channel matrixsingular vector or eigen vector. This eigenmode is a method that usesthese singular vectors or eigen vectors as aforementioned channelsignature vectors. A channel matrix here is a matrix that has complexchannel coefficients of a combination of all or some of the antennaelements of the transmitting array antenna and antenna elements of thereceiving array antenna as elements.

As a method whereby the transmitting station obtains downlink channelstate information, with TDD, in which carriers of the same frequency areused in a radio channel uplink and downlink, it is possible to performestimating or measuring of channel state information in the transmittingstation using the uplink from the transmitting station by means ofchannel reciprocity. On the other hand, with FDD, in which carriers ofdifferent frequencies are used in the uplink and downlink, it ispossible to obtain accurate downlink CSI in the transmitting station byestimating or measuring downlink channel state information in thereceiving station.

A feature of the eigenmode is that, particularly when a MIMO systemradio channel is handled as a narrowband flat fading process, MIMOsystem channel capacity can be maximized. For example, in a radiocommunication system that uses OFDM, it is usual for design to becarried out so that guard intervals are inserted in order to eliminateinter-symbol interference due to multipath delayed waves, and each OFDMsubcarrier is a flat fading process. Therefore, when an OFDM signal istransmitted in a MIMO system, by using the eigenmode it is possible, forexample, to transmit a plurality of signals multiplexed spatially ineach subcarrier.

As a communication method that uses a MIMO system, several methods havebeen proposed whereby, in contrast to the eigenmode in which downlinkchannel state information is known in the transmitting station andreceiving station, channel state information for a radio channel isknown only in the receiving station. BLAST, for example, is known as amethod whereby signals are transmitted and are multiplexed spatially forthe same purpose as with the eigenmode. Also, transmission diversityusing space-time coding, for example, is known as a method whereby thedegree of signal multiplexing is sacrificed—that is, as a method not forincreasing capacity but whereby a so-called antenna space diversityeffect is obtained. While the eigenmode is a beam space mode whereby asignal is transmitted vectored by a transmitting array antenna—in otherwords, a signal is transmitted mapped onto beam space—BLAST and spacediversity can be thought of as antenna element modes since mapping isperformed onto antenna elements.

In Embodiment 13 of the present invention, a description has been givenof a transmission method for a pilot signal for demodulation in a casewhere, in a MIMO system, a transmitting station transmits modulatedsignals to a receiving station mainly using an eigenmode, but the effectdescribed later herein can be obtained in a similar way when anothermethod that unitizes an antenna element mode is used.

FIG. 60 is a drawing showing a sample configuration of a channelmultiplexing communication system using a beam space mode typified by aneigenmode in a MIMO system. In the transmitting station, a multiplexframe generation section 5901 has a transmit data sequence as input, andgenerates a plurality of transmit frames for mapping onto multiplexchannels. Based on channel state information comprising estimationresults for propagation channels between the transmitting station andreceiving station, a transmission channel analysis section 5902calculates a plurality of transmission channel signature vectors forconfiguring multiplex channels. A vector multiplexing section 5903multiplies individual transmit frames by the respective channelsignature vectors and combines them, and then transmits the resultingsignals to the receiving station from a transmitting array antenna 5904.

In the receiving station, a reception channel analysis section 5911calculates a plurality of reception channel signature vectors forseparating multiplexed transmit signals based on channel stateinformation comprising estimation results for propagation channelsbetween the transmitting station and receiving station. A multiplexsignal separation section 5913 has received signals from a receivingarray antenna 5912 as input, multiplies these by the respective channelsignature vectors, and generates a plurality of obtained received signalframes. A multiframe combining section 5914 gathers together the signalsmapped onto the multiplex channels, and composes a receive datasequence.

In a communication method of the present invention, a symbol of onechannel is transmitted at a first frequency, and symbols of a pluralityof channels modulated by means of a different modulation method aremultiplexed and transmitted at a second frequency.

In a communication method of the present invention, information onpropagation path conditions estimated by a communicating party isreceived, a symbol is transmitted at a first frequency to a firstcommunicating party, and a symbol is transmitted at a second frequencyto a communicating party whose propagation path conditions are worsethan those of the first communicating party.

A communication method of the present invention is characterized in thata symbol transmitted at a first frequency has a higher degree ofimportance in communication than a symbol transmitted at a secondfrequency.

In a communication method of the present invention, first data istransmitted at a first frequency, a difference between second data andfirst data is generated, and the difference is transmitted at a secondfrequency.

In a communication method of the present invention, a symbol of onechannel is transmitted at a first frequency at the start ofcommunication, and after information on propagation path conditionsestimated by a communicating party is received, symbols are transmittedat the first frequency and a second frequency.

In a communication method of the present invention, a known symbol istransmitted at the start of communication, and information onpropagation path conditions estimated by a communicating party usingthat known symbol is received.

A transmitting apparatus of the present invention has a configurationcomprising a first modulation section that modulates a signal of a firstchannel and generates a first symbol, a second modulation section thatmodulates a signal of a second channel and generates a second symbol, afirst transmitting section that transmits the first symbol at a firstfrequency, and a second transmitting section that multiplexes the firstsymbol and the second symbol and transmits the multiplexed symbols at asecond frequency.

A transmitting apparatus of the present invention has a configurationcomprising a receiving section that receives information on propagationpath conditions estimated by a communicating party, and a determinationsection that determines transmission of a symbol by a first transmittingsection to a first communicating party and transmission of a symbol by asecond transmitting section to a communicating party whose propagationpath conditions are worse than those of the first communicating partybased on propagation path conditions of a plurality of communicatingparties.

A transmitting apparatus of the present invention has a configurationwherein a first transmitting section transmits a symbol of a higherdegree of importance in communication than a symbol transmitted by asecond transmitting apparatus.

A transmitting apparatus of the present invention has a configurationwherein a first transmitting section transmits a symbol of a firstchannel at a first frequency at the start of communication, and afterinformation on propagation path conditions estimated by a communicatingparty is received, a second transmitting section transmits a symbol at asecond frequency.

A transmitting apparatus of the present invention has a configurationwherein a first transmitting section transmits a known symbol at thestart of communication, and a receiving section receives information onpropagation path conditions estimated by a communicating party usingthat known symbol.

A receiving apparatus of the present invention has a configurationcomprising a first receiving section that receives at a first frequencya radio signal in which a symbol of one channel is modulated, a secondreceiving section that receives at a second frequency a radio signal inwhich symbols of a plurality of channels modulated by means of adifferent modulation method are multiplexed, a first demodulationsection that demodulates a signal received by means of a first carrier,a second demodulation section that demodulates a signal received bymeans of a second carrier, and a separation section that separates asignal demodulated by the second demodulation section on achannel-by-channel basis.

A receiving apparatus of the present invention has a configurationcomprising an estimation section that estimates propagation pathconditions based on a known symbol of a radio signal received by a firstreceiving section, and a transmitting section that transmits informationon propagation path conditions estimated by the estimation section.

In a communication method of the present invention, a symbol of onechannel is transmitted at a first time, and symbols of a plurality ofchannels modulated by means of a different modulation method aremultiplexed and transmitted at a second time.

In a communication method of the present invention, information onpropagation path conditions estimated by a communicating party isreceived, a symbol is transmitted at a first time to a firstcommunicating party, and a symbol is transmitted at a second time to acommunicating party whose propagation path conditions are worse thanthose of the first communicating party.

A communication method of the present invention is characterized in thata symbol transmitted at a first time has a higher degree of importancein communication than a symbol transmitted at a second time.

In a communication method of the present invention, first data istransmitted at a first time, a difference between second data and firstdata is generated, and the difference is transmitted at a second time.

In a communication method of the present invention, a symbol of onechannel is transmitted at a first time at the start of communication,and after information on propagation path conditions estimated by acommunicating party is received, symbols are transmitted at the firsttime and a second time.

In a communication method of the present invention, a known symbol istransmitted at the start of communication, and information onpropagation path conditions estimated by a communicating party usingthat known symbol is received.

A transmitting apparatus of the present invention has a configurationcomprising a first modulation section that modulates a signal of a firstchannel and generates a first symbol, a second modulation section thatmodulates a signal of a second channel and generates a second symbol, afirst transmitting section that transmits the first symbol at a firsttime, and a second transmitting section that multiplexes the firstsymbol and the second symbol and transmits the multiplexed symbols at asecond time.

A transmitting apparatus of the present invention has a configurationcomprising a receiving section that receives information on propagationpath conditions estimated by a communicating party, and a determinationsection that determines transmission of a symbol by a first transmittingsection to a first communicating party and transmission of a symbol by asecond transmitting section to a communicating party whose propagationpath conditions are worse than those of the first communicating partybased on propagation path conditions of a plurality of communicatingparties.

A transmitting apparatus of the present invention has a configurationwherein a first transmitting section transmits a symbol of a higherdegree of importance in communication than a symbol transmitted by asecond transmitting apparatus.

A transmitting apparatus of the present invention has a configurationwherein a first transmitting section transmits a symbol of a firstchannel at a first time at the start of communication, and afterinformation on propagation path conditions estimated by a communicatingparty is received, a second transmitting section transmits a symbol at asecond time.

A transmitting apparatus of the present invention has a configurationwherein a first transmitting section transmits a known symbol at thestart of communication, and a receiving section receives information onpropagation path conditions estimated by a communicating party usingthat known symbol.

A receiving apparatus of the present invention has a configurationcomprising a first receiving section that receives at a first time aradio signal in which a symbol of one channel is modulated, a secondreceiving section that receives at a second time a radio signal in whichsymbols of a plurality of channels modulated by means of a differentmodulation method are multiplexed, a first demodulation section thatdemodulates a signal received by means of a first carrier, a seconddemodulation section that demodulates a signal received by means of asecond carrier, and a separation section that separates a signaldemodulated by the second demodulation section on a channel-by-channelbasis.

A receiving apparatus of the present invention has a configurationcomprising an estimation section that estimates propagation pathconditions based on a known symbol of a radio signal received by a firstreceiving section, and a transmitting section that transmits informationon propagation path conditions estimated by the estimation section.

As is clear from the above description, according to a communicationmethod of the present invention and a transmitting apparatus andreceiving apparatus that use that communication method, by transmittinginformation of a high degree of importance by means of a method wherebyone modulated signal of a communication system is transmitted byconfiguring in accordance with either a method whereby one modulatedsignal of a communication system is transmitted, or a method whereby aplurality of modulated signals of a communication system are multiplexedand transmitted, by frequency and time, an effect is achieved ofenabling a communicating party communicating party to obtain informationaccurately. Also, by performing communication by frequency or time of amethod whereby one modulated signal of a communication system istransmitted, and by frequency or time of a method whereby a plurality ofmodulated signals of a communication system are multiplexed andtransmitted, according to the communication conditions, an effect isachieved of enabling information transmission speed and received dataquality to be made compatible.

This application is based on Japanese Patent Application No. 2000-206799filed on Jul. 16, 2002, and Japanese Patent Application No. 2000-259791filed on Sep. 5, 2002, entire content of which is expressly incorporatedby reference herein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a radio communication apparatus,base station apparatus, and communication terminal apparatus.

1. A method for use in a communication apparatus that receives anorthogonal frequency division multiplexing (OFDM) signal transmittedfrom a base station, the OFDM signal including a plurality of carriergroups each comprising a plurality of carriers, the plurality of carriergroups being assigned transmission data for a plurality of communicationapparatuses, and each of the plurality of carrier groups adopting one ofa first frame configuration where the transmission data is transmittedusing one modulation signal and a second frame configuration where thetransmission data is transmitted using a plurality of modulated signals,the method comprising: specifying a carrier group to which transmissiondata for the communication apparatus is assigned, based on controlinformation included in the received OFDM signal; and generatingreception data associated with the specified carrier group based on oneof the one modulated signal used in the first frame configuration andthe plurality of modulated signals used in the second frameconfiguration.
 2. The method according to claim 1, further comprising:estimating a propagation path condition from the OFDM signal; andtransmitting radio wave propagation environment information related tothe estimated propagation path condition.
 3. The method according toclaim 2, wherein the radio wave propagation environment informationcomprises one of field strength and channel state information.
 4. Themethod according to claim 1, wherein the modulated signal comprises: adata symbol for transmitting transmission data to one of the pluralityof communication apparatuses; and a control symbol located before thedata symbol on a time axis, the control symbol being used to decode thetransmission data by the communication apparatus which received themodulated signal.
 5. The method according to claim 1, wherein themodulated signal comprises: a data symbol for transmitting transmissiondata to one of the plurality of communication apparatuses; and anestimation symbol located before the data symbol on a time axis, theestimation symbol being used to estimate one of time synchronization,frequency synchronization, and channel distortion of the modulatedsignal.
 6. The method according to claim 1, wherein the OFDM signal isreceived using a plurality of antennas in the communication apparatus.7. The method according to claim 1, wherein, when the second frameconfiguration is adopted, the plurality of modulated signals aretransmitted from a plurality of antennas of the base station.
 8. Themethod according to claim 7, wherein, when the second frameconfiguration is adopted, the plurality of modulated signals aretransmitted at an identical time period over an identical frequency bandby using the plurality of antennas of the base station.
 9. Acommunication apparatus that receives an orthogonal frequency divisionmultiplexing (OFDM) signal transmitted from a base station, the OFDMsignal including a plurality of carrier groups each comprising aplurality of carriers, the plurality of carrier groups being assignedtransmission data for a plurality of communication apparatuses, and eachof the plurality of carrier groups adopting one of a first frameconfiguration where the transmission data is transmitted using onemodulation signal and a second frame configuration where thetransmission data is transmitted using a plurality of modulated signals,the communication apparatus comprising: an input to which the receivedOFDM signal is input; and a demodulator configured to specify a carriergroup to which transmission data for the communication apparatus isassigned, based on control information included in the received OFDMsignal, and to generate reception data associated with the specifiedcarrier group based on one of the one modulated signal used in the firstframe configuration and the plurality of modulated signals used in thesecond frame configuration.
 10. The communication apparatus according toclaim 9, further comprising: a propagation path estimator whichestimates a propagation path condition from the received signal; and atransmitter which transmits radio wave propagation environmentinformation related to the estimated propagation path condition.
 11. Thecommunication apparatus according to claim 10, wherein the radio wavepropagation environment information comprises one of field strength andchannel state information.
 12. The communication apparatus according toclaim 9, wherein the modulated signal comprises: a data symbol fortransmitting transmission data to one of the plurality of communicationapparatuses; and a control symbol located before the data symbol on atime axis, the control symbol being used to decode the transmission databy the communication apparatus which received the modulated signal. 13.The communication apparatus according to claim 9, wherein the modulatedsignal comprises: a data symbol for transmitting transmission data toone of the plurality of communication apparatuses; and an estimationsymbol located before the data symbol on a time axis, the estimationsymbol being used to estimate one of time synchronization, frequencysynchronization, and channel distortion of the modulated signal.
 14. Thecommunication apparatus according to claim 9, wherein the OFDM signal isreceived using a plurality of antennas in the communication apparatus.15. The communication apparatus according to claim 9, wherein, when thesecond frame configuration is adopted, the plurality of modulatedsignals are transmitted over a plurality of antennas of the basestation.
 16. The communication apparatus according to claim 15, wherein,when the second frame configuration is adopted, the plurality ofmodulated signals are transmitted at an identical time period over anidentical frequency band by using the plurality of antennas of the basestation.